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  • 1
    ISSN: 1573-5028
    Keywords: glycine betaine ; betaine aldehyde dehydrogenase ; osmotic stress ; gene expression ; plant hormone ; abscisic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When subjected to salt stress or drought, some vascular plants such as barley respond with an increased accumulation of the osmoprotectant glycine betaine (betaine), being the last step of betaine synthesis catalyzed by betaine aldehyde dehydrogenase (BADH). We report here cloning and characterization of BADH cDNA from barley, a monocot, and the expression pattern of a BADH transcript. An open reading frame of 1515 bp encoded a protein which showed high homology to BADH enzymes present in other plants (spinach and sugar-beet) and in Escherichia coli. Transgenic tobacco plants harboring the clone expressed high levels of both BADH protein and its enzymatic activity. Northern blot analyses indicated that BADH mRNA levels increased almost 8-fold and 2-fold, respectively, in leaves and roots of barley plants grown in high-salt conditions, and that these levels decreased upon release of the stress, whereas they did not decrease under continuous salt stress. BADH transcripts also accumulate in response to water stress or drought, indicating a common response of the plant to osmotic changes that affect its water status. The addition of abscisic acid (ABA) to plants during growth also increased the levels of BADH transcripts dramatically, although the response was delayed when compared to that found for salt-stressed plants. Removal of plant roots before transferring the plants to high-salt conditions reduced only slightly the accumulation of BADH transcripts in the leaves.
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  • 2
    ISSN: 1573-5028
    Keywords: rice seed storage protein ; albumin ; gene expression ; glutelin ; prolamin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of rice seed storage-protein genes is dramatically regulated over a short period of seed maturation. To characterize the expression mechanism of the rice seed storage protein genes, their expression of major storage protein genes (16 kDa albumin, 13 kDa prolamin and type II glutelin) were compared by RNA blot analysis. Their coordinate expression suggests that the transcriptional regulatory machinery is shared among the glutelin, prolamin and albumin-genes. We isolated two novel genomic genes for prolamins (PG5a and PG5b) and obtained the promoter region of the glutelin gene by PCR. The 5′-flanking regions of these three rice seed storage protein genes were found to contain some similar conserved sequences. Nuclear extract partially purified from maturing rice seeds was used for the gel shift assay of the 5′ region of the RA gene. We identified two DNA sequences of RA gene which were recognized by independent DNA-binding proteins. The complexes of these DNA sequences and DNA-binding proteins were inhibited by the fragments containing the 5′ regions of the prolamin and glutelin genes, suggesting that these three genes share transcription factors.
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  • 3
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; chloroplast ; gene expression ; ω-3 fatty acid desaturase ; promoter ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Arabidopsis FAD7 gene encodes a chloroplast ω-3 fatty acid desaturase that catalyzes the desaturation of lipid-linked dienoic fatty acids (18:2 and 16:2). An 825 bp FAD7 promoter fragment upstream from the transcriptional start point contained several short sequences which were homologous to the cis-elements (box II, G-box, etc.) conserved in many light-responsive genes. We introduced the FAD7 promoter fused to the β-glucuronidase (GUS) or the luciferase (LUC) reporter gene into tobacco plants. The −825 promoter sequence conferred tissue-specific and light-responsive expression to both these reporter genes in transgenic tobacco, indicating that these expressions of the FAD7 gene were regulated mainly at the transcriptional level. Histochemical GUS staining showed that the activity of the FAD7 promoter is restricted to the tissues with chloroplast-containing cells although the staining was noticeably absent in the chloroplast-containing cells associated with vascular systems. The 5′ deletion experiments of the promoter revealed that the −362/ −166 region, containing two putative box II sequences, was responsible for the tissue-specific and light-responsive expression of the FAD7 gene.
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  • 4
    ISSN: 1573-5028
    Keywords: Nicotiana tabacum ; tobacco BY-2 cells ; gene expression ; jasmonic acid ; methyl jasmonate ; ornithine decarboxylase ; polyamine ; nicotine ; SAM synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA of tobacco BY-2 cells corresponding to an mRNA species which was rapidly induced by methyl jasmonate (MeJA) in the presence of cycloheximide (CHX) was found to encode ornithine decarboxylase (ODC). Another cDNA from a MeJA-inducible mRNA encoded S-adenosylmethionine synthase (SAMS). Although these enzymes could be involved in the biosynthesis of polyamines, the level of putrescine, a reaction product of ODC, increased slowly and while the levels of spermidine and spermine did not change following treatment of cells with MeJA. However, N-methylputrescine, which is a precursor of pyrrolidine ring of nicotine, started to increase shortly after MeJA-treatment of cells and the production of nicotine occured thereafter. The levels of mRNA for arginine decarboxylase (ADC), an alternative enzyme for putrescine synthesis, and that for S-adenosylmethionine decarboxylase (SAMDC), required for polyamine synthesis, were not affected by MeJA. In addition to mRNAs for ODC and SAMS, mRNA for putrescine N-methyltransferase (PMT) was also induced by MeJA. Unlike the MeJA-induction of ODC mRNA, MeJA-induction of SAMS and PMT mRNAs were blocked by CHX. The level of ODC mRNA declined after 1 to 4 h following MeJA treatment, while the levels of mRNAs for SAMS and PMT continued to increase. Auxin significantly reduced the MeJA-inducible accumulation of mRNAs for ODC, SAMS and PMT. These results indicate that MeJA sequentially induces expression of a series of genes involved in nicotine biosynthesis by multiple regulatory mechanisms.p〉
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-7241
    Keywords: ventricular remodeling ; myocardial infarction ; diltiazem ; Doppler echocardiography ; gene expression ; cardiac function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Summary. The purpose of this study was to examine the effect of diltiazem on cardiac dysfunction and the change in cardiac gene expression after myocardial infarction in rats. On the first day after myocardial infarction, rats were randomly assigned to a diltiazem treatment (Dil, n = 7) or an untreated group (MI, n = 8). We then performed Doppler-echocardiographic examinations on the rats and measured their hemodynamics at 4 weeks after myocardial infarction. Following these measurements, their cardiac mRNA was analyzed. Diltiazem decreased the mean aortic pressure and heart rate. Left ventricular end-diastolic pressure (LVEDP) and central venous pressure (CVP) increased to 18 ± 2 mmHg and 5 ± 1 mmHg (P 〈 0.01). Diltiazem reduced LVEDP to 14 ± 1 mmHg (P 〈 0.05), but it did not change CVP. The weight of the right ventricle in MI was significantly larger than in the control rats (control, n = 7, 0.46 ± 0.02 g/kg vs. MI, 0.81 ± 0.06 g/kg; P 〈 0.01). The left ventricular end-diastolic dimension (LVDd) in MI increased to 8.8 ± 0.3 mm (P 〈 0.01, control, 6.1 ± 0.3 mm). Diltiazem prevented an increase in the weight of the right ventricle (0.69 ± 0.03 g/kg, P 〈 0.05) and LVDd (7.7 ±6 0.2 mm, P 〈 0.05 to MI). The rats within MI showed systolic dysfunction, defined by a decreased ejection fraction (control, 67 ± 2% vs. MI, 36 ± 3%, P 〈 0.01), and diastolic dysfunction, defined by the E-wave deceleration rate (control, 13.4 ± 1.6 m/s2 vs. MI, 30.4 ± 3.4 m/s2 P 〈 0.01). Diltiazem significantly prevented systolic and diastolic dysfunction. The increases in β-MHC, ANP, and collagen type I and III mRNAs in the noninfarcted left ventricle and right ventricle were significantly suppressed by treatment with diltiazem. α-Skeletal actin increased in MI, and α-skeletal actin was more increased with Dil. In conclusion, diltiazem prevents cardiac dysfunction and morphological change due to left ventricular remodeling after experimental myocardial infarction.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 38 (1997), S. 121-127 
    ISSN: 0021-9304
    Keywords: titanium metal ; NaOH treatment ; bioactivity ; apatite ; simulated body fluid ; bonding strength ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Our previous study showed that titanium metal forms a bonelike apatite layer on its surface in simulated body fluid when it was subjected to NaOH and heat treatments to form a sodium titanate hydrogel or amorphous sodium titanate surface layer. In the present study, bonding strength of the apatite layer formed on the titanium metals to the substrates were examined under tensile stress, in comparison with those of the apatite layers formed on Bioglass 45S5-type glass, dense sintered hydroxyapatite, and glass-ceramic A-W, which are already clinically used. The NaOH-treated titanium metals showed higher bonding strength of the apatite layer to the substrates, which was maximized by heat treatments at 500 and 600 °C, than all the examined bioactive ceramics. It is believed that bioactive metals thus obtained are useful as bone substitutes, even under load-bearing conditions. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 38: 121-127, 1997
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 145-152 
    ISSN: 0021-9304
    Keywords: bioactive bone cement ; Bis-GMA resin ; AW glass-ceramic ; mechanical properties ; bioactivity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We examined the influence of the proportion of glass-ceramic powder in a bioactive bone cement of our formula on the bone-bonding ability of cement. Changes in cement bonding with time also were examined. The bioactive bone cement consisted of MgO-CaO-SiO2-P2O5-CaF2 glass-ceramic powder (AW-GC powder) and bisphenol-α-glycidyl methacrylate (Bis-GMA)-based resin. AW-GC powder was added to the cement as 0%, 30%, 50%, 70%, and 80% w/w. Rectangular plates (2 × 10 × 15 mm) of each cement with polished surfaces were implanted into the proximal metaphysis of the tibiae of male rabbits, and the failure load was measured by detaching tests 10 and 25 weeks after implantation. The failure loads of each cement were 0% = 0.03, 30% = 1.52, 50% = 2.67, 70% = 3.56, and 80% = 5.59 kg at 10 weeks, and 0% = 0.05, 30% = 1.68, 50% = 2.77, 70% = 3.80, and 80% = 6.37 kg at 25 weeks. Observation of the cement-bone interface revealed that all bioactive bone cements (30%-80%) formed direct contact with bone whereas intervening fibrous tissue was observed in all specimens of the 0% group. By scanning electron microscopy, all bioactive bone cements (30%-80% groups) showed direct contact with bone at the cement-bone interface. In the 0% group, direct contact with bone at the cement-bone interface was not observed. By electron-probe microanalysis, a Ca-P-rich layer was not detected at the cement-bone interfaces of the 30%-70% bioactive bone cements, but in some samples of the 80% cement specimens a thin Ca-P-rich layer (3 μm thick) was observed at the interface at 10 and 25 weeks after implantation. These results show that all of the bioactive bone cements tested had the ability to bond to bone and to function as bioactive composites of ceramics and polymers. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 145-152, 1998.
    Additional Material: 5 Ill.
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  • 8
    ISSN: 0021-9304
    Keywords: bioactive bone cement ; inhibitor ; accelerator ; mechanical properties ; bioactivity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We introduced an inhibitor to the polymerization reaction of bioactive bone cement (AWC) consisting of MgO - CaO - SiO2 - P2O5 - CaF2 apatite and wollastonite containing glass-ceramic powder and bisphenol-α-glycidyl methacrylate based resin, together with an increased amount of accelerator but without any prolongation of its setting time in order to improve the degree of polymerization and decrease the amount of incompletely polymerized monomers on the cement surface. A comparison was made between the AWC containing the inhibitor [AWC(I+)] and the AWC without it [AWC(I-)] with regard to setting parameters, mechanical properties, and surface reactivity in vitro and in vivo. The proportion of glass-ceramic powder added to the AWC was 70% (w/w). The total amount of heat generation and the peak temperature of the AWC(I+) during polymerization were slightly greater than those of the AWC(I-). The mechanical strength of AWC(I+) was higher than that of the AWC(I-) under wet conditions. In simulated body fluid, the width of the Ca-P rich layer on the surface of the AWC(I+) was less than that on the AWC(I-) after 28 days of immersion, although the rate of apatite formation on the top surface of the AWC(I+) was almost identical to that on the AWC(I-) surface. Histological examination using rat tibiae up to 26 weeks revealed that the bioactivity of the AWC(I+) was equivalent to that of the AWC(I-). Scanning electron microscopy and energy-dispersive X-ray microanalysis demonstrated that the Ca-P rich layer in the AWC(I+) was significantly narrower than that in the AWC(I-) at the same time points. These results indicate that introduction of the inhibitor improved the mechanical properties of the AWC and made the Ca-P rich layer narrower, but it had no adverse effect on bioactivity. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 140-152, 1998
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 42 (1998), S. 604-610 
    ISSN: 0021-9304
    Keywords: apatite ; composite cement ; bioactivity ; simulated body fluid ; resin ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Recently much attention has been paid to bioactive filler-resin composite cements because they can solidify in a few minutes to give high mechanical strengths and they can bond to living bone. In this study the dependence on resin of apatite-forming ability in simulated body fluid (SBF) was investigated for the composite cements of bioactive CaO-SiO2-P2O5-CaF2 glass with polymethyl methacrylate (PMMA) or bisphenol-a-glycidyl methacrylate/triethyleneglycol (Bis-GMA/TEGDMA) resin. The PMMA-containing composite cement did not show the apatite-forming ability in SBF because the reaction of the glass grains with SBF was inhibited due to the complete covering of the grains with PMMA. To the contrary, the Bis-GMA/TEGDMA-containing cement exhibited high apatite-forming ability in SBF; these monomers significantly dissolved from the composite surface into SBF, causing a direct exposure of the glass grains to SBF to convert into silica gel. It is assumed that thus formed silica gels, and the silicate ions that were dissolved and adsorbed onto the composite surface, induced the apatite nucleation between the spaces of the glass grains and on the composite surface, respectively. A continuous bone-like apatite layer was formed on the top surface of the glass-Bis-GMA/TEGDMA composite cement in a short period. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 42, 604-610, 1998.
    Additional Material: 6 Ill.
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  • 10
    ISSN: 0021-9304
    Keywords: bioactive bone cement ; AW glass-ceramic ; silica ; bioactivity ; mechanical properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Silica glass powder (SG-P) made by a fusing-quenching method was added as a second filler to a bioactive bone cement consisting of MgO-CaO-SiO2-P2O5-CaF2 apatite and wollastonite containing glass-ceramic powder (AW-P) and bisphenol-a-glycidyl methacrylate (Bis-GMA)-based resin, to achieve a higher mechanical strength and better handling properties in use. Five types of cement were used, containing different weight ratios of AW-P/SG-P (Group 1 = 100/0; Group 2 = 75/25; Group 3 = 50/50; Group 4 = 25/75; and Group 5 = 0/100) as filler, to evaluate the effect of SG-P content on the biological, mechanical, and handling properties. The total proportion of filler added to the cements was 85% w/w. The compressive, bending, and tensile strengths and fracture toughness of the cements increased with SG-P content. The viscosity of cements also increased with SG-P content, and every cement could be handled manually. The cements were evaluated in vivo by packing the intramedullary canals of rat tibiae. An affinity index was calculated for each cement; this was the length of bone directly apposed to cement expressed as a percentage of the total length of the cement surface. Histological examination of implanted tibiae for up to 26 weeks showed that the affinity indices decreased with SG-P content and that those of all the cement groups increased with time. At 26 weeks, Groups 1 and 2 had almost identical affnity indices (79% and 75%; no significant difference) but those of the other groups remained at 〈50%. Group 2 had better mechanical and handling properties than Group 1, and an SG-P content in the filler of no more than 25% w/w did not interfere strongly with the bioactivity of the cement. © John Wiley & Sons, Inc. J Biomed Mater Res, 37, 68-80, 1997.
    Additional Material: 8 Ill.
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