Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BORATES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed1999

Borate-rhamnogalacturonan II bonding reinforced by Ca2+ retains pectic polysaccharides in higher-plant cell walls

The extent of in vitro formation of the borate-dimeric-rhamnogalacturonan II (RG-II) complex was stimulated by Ca2+. The complex formed in the presence of Ca2+ was more stable than that without Ca2+. A naturally occurring boron (B)-RG-II complex isolated from radish (Raphanus sativus L. cv Aokubi-daikon) root contained equimolar amounts of Ca2+ and B. Removal of the Ca2+ by trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid induced cleavage of the complex into monomeric RG-II. These data suggest that Ca2+ is a normal component of the B-RG-II complex. Washing the crude cell walls of radish roots with a 1.5% (w/v) sodium dodecyl sulfate solution, pH 6.5, released 98% of the tissue Ca2+ but only 13% of the B and 22% of the pectic polysaccharides. The remaining Ca2+ was associated with RG-II. Extraction of the sodium dodecyl sulfate-washed cell walls with 50 mM trans-1,2-diaminocyclohexane-N, N,N',N'-tetraacetic acid, pH 6.5, removed the remaining Ca2+, 78% of B, and 49% of pectic polysaccharides. These results suggest that not only Ca2+ but also borate and Ca2+ cross-linking in the RG-II region retain so-called chelator-soluble pectic polysaccharides in cell walls.

Journal Article↗
PubMed1999

The Pore Size of Non-Graminaceous Plant Cell Walls Is Rapidly Decreased by Borate Ester Cross-Linking of the Pectic Polysaccharide Rhamnogalacturonan II.

The walls of suspension-cultured Chenopodium album L. cells grown continually for more than 1 year on B-deficient medium contained monomeric rhamnogalacturonan II (mRG-II) but not the borate ester cross-linked RG II dimer (dRG-II-B). The walls of these cells had an increased size limit for dextran permeation, which is a measure of wall pore size. Adding boric acid to growing B-deficient cells resulted in B binding to the wall, the formation of dRG-II-B from mRG-II, and a reduction in wall pore size within 10 min. The wall pore size of denatured B-grown cells was increased by treatment at pH </= 2.0 or by treatment with Ca(2+)-chelating agents. The acid-mediated increase in wall pore size was prevented by boric acid alone at pH 2.0 and by boric acid together with Ca(2+), but not by Na(+) or Mg(2+) ions at pH 1.5. The Ca(2+)-chelator-mediated increase in pore size was partially reduced by boric acid. Our results suggest that B-mediated cross-linking of RG-II in the walls of living plant cells generates a pectin network with a decreased size exclusion limit for polymers. The formation, stability, and possible functions of a borate ester cross-linked pectic network in the primary walls of nongraminaceous plant cells are discussed.

Journal Article↗
PubMed2003

An alkoxide cluster with 18 Li+ ions encapsulating two borate anions, [((t)BuO)12Li18(BO3)2].

The title compound, bis(borato)dodeca(tert-butoxo)octadecalithium, [Li(18)(BO(3))(2)(C(4)H(9)O)(12)], is formulated conveniently as [(((t)BuOLi)(3)(Li(3)BO(3)))(2)((t)BuOLi)(6)]. A central 12-membered ring and two outer six-membered rings are formed by alternating Li(+) cations and alkoxide O atoms. Sandwiched between the central ring and each of the outer rings is a planar array of three further Li(+) cations surrounding a [BO(3)](3-) anion. Thus, the molecule consists of a cationic [Li(18)(O(t)Bu)(12)](6+) cage encapsulating two borate anions. This compound is the first example of a structurally characterized polynuclear lithium borate, and a rare case of a lithium alkoxide cage with nuclearity greater than eight. All the alkoxide ligands are triply bridging, and the lithium ions have trigonal-planar, trigonal-pyramidal and fourfold coordination, all with major distortions from regular coordination geometry.

Journal Article↗
PubMed2003

Structures of potassium, sodium and lithium bis(oxalato)borate salts from powder diffraction data.

The crystal structures of the alkali-metal bis(oxalato)borate salts A[B(C2O4)2] (A = K, Na, Li) have been determined ab initio using powder diffraction data obtained from a laboratory diffractometer. The K compound crystallizes in the orthorhombic space group Cmcm and its structure has been solved by direct methods applied to the integrated intensities from full pattern decomposition. The Na compound is isostructural with the K salt, while the crystal structure of the highly hydroscopic Li compound differs from the other two. It has an orthorhombic lattice, space group Pnma, and its structure was solved by the global optimization method using a parallel tempering approach. In the K and Na structures the metal ions and complex borate ions form chains with m2m symmetry. Metal-oxygen bonding between the chains links them into a layer and then a framework with square tunnels. The coordination number of both K and Na is eight. The Li compound also contains chains that have .m. symmetry and are bound together into a three-dimensional framework. The coordination polyhedron of the Li atom is a square pyramid with Li lying in its base. This square pyramidal coordination leads to its high reactivity with moisture to give Li[B(C2O4)2]H2O with lithium in six coordination.

Journal Article↗
PubMed2004

Rhamnogalacturonan II: structure and function of a borate cross-linked cell wall pectic polysaccharide.

Rhamnogalacturonan II (RG-II) is a structurally complex pectic polysaccharide that was first identified in 1978 as a quantitatively minor component of suspension-cultured sycamore cell walls. Subsequent studies have shown that RG-II is present in the primary walls of angiosperms, gymnosperms, lycophytes, and pteridophytes and that its glycosyl sequence is conserved in all vascular plants examined to date. This is remarkable because RG-II is composed of at least 12 different glycosyl residues linked together by more than 20 different glycosidic linkages. However, only a few of the genes and proteins required for RG-II biosynthesis have been identified. The demonstration that RG-II exists in primary walls as a dimer that is covalently cross-linked by a borate diester was a major advance in our understanding of the structure and function of this pectic polysaccharide. Dimer formation results in the cross-linking of the two homogalacturonan chains upon which the RG-II molecules are constructed and is required for the formation of a three-dimensional pectic network in muro. This network contributes to the mechanical properties of the primary wall and is required for normal plant growth and development. Indeed, changes in wall properties that result from decreased borate cross-linking of pectin may lead to many of the symptoms associated with boron deficiency in plants.

Cycadopsida↗
PubMed2003

Noncritically phase-matched second-harmonic generation in cesium lithium borate.

Efficient generation of 236-nm light was demonstrated by use of noncritically phase-matched second-harmonic generation in cesium lithium borate. Noncritical phase matching provided approximately 20x the nonlinear drive for second-harmonic generation than beta-barium borate for 236-nm generation. The 236-nm wavelength is the fourth harmonic of a 946-nm Nd:YAG laser. Phase matching was accomplished at a crystal temperature of -15 degrees C.

Journal Article↗
PubMed1999

[Luminescence character of Ce3+ in rare earth borate glasses].

Ce3+ doped rare earth borate glasses (BLBL:Ce3+) were synthesized. The excitation and emission spectra and fluorescence decay curves of BLBL:Ce3+ were measured at room temperature. In BLBL:Ce3+ glasses, Ce3+ emits strong purplish-blue light. The results of analyzing spectra and fluorescence lifetime show that there are two kinds of Ce3+ luminescence centres in this kind of rare earth borate glasses. Ce3+ doped rare-earth glasses is a kind of beneficial supplement for Ce3+ fluorescence glasses system.

English Abstract↗
PubMed2006

[Calculation of optical parameters and investigation of luminescence spectra in Sm3+ doped borate glasses].

In the present paper, Sm3+ doped borate glasses (LBLB) with high effective visible fluorescence emission have been synthesized. The absorption and fluorescence spectra of this glass were measured and analyzed. The absorption spectra were fitted by J-O theory, and the intensity parameters omega = (2, 4, 6) were found to be 6.81 x 10(-20), 4.43 x 10(-20), and 2.58 x 10(-20) cm2, respectively, then the relative intensity of spectral lines of every energy level transition, radiative transition probabilities, radiative lifetimes, and fluorescence branching ratio were calculated. Under the excitation of UV light, Sm3+ doped borate glasses (LBLB) emit bright salmon pink light. The excitation spectra indicate that argon laser is an effective excitation source in Sm3+ doped LBLB glasses.

English Abstract↗
PubMed1994

Removal of borate from tritiated gangliosides via the mannitoborate complex.

Purified gangliosides were radiolabeled by exposure to sodium boro [3H]hydride in the presence of palladium on barium sulfate. After centrifugation to remove the catalyst, borate was complexed with mannitol and the resulting mannitoborate complex and salts were removed by reversed phase chromatography. The labeled gangliosides were repurified by ion exchange and silica gel chromatographies. Radiopurity was determined by autoradiography of two-dimensional thin-layer chromatograms of the gangliosides. The method eliminates the need for extensive dialysis or repeated methanol evaporations to remove borate thus reducing time and the volume of labeled waste.

Autoradiography↗
PubMedDate not supplied

High-performance capillary electrophoretic separation of carbohydrates with indirect UV detection using diethylamine and borate as electrolyte additives.

The separation of underivatized carbohydrates was investigated using capillary zone electrophoresis with indirect UV detection based on sorbic acid or riboflavin. In comparison with sodium hydroxide, the separation of carbohydrates was greatly improved using diethylamine (DEA) as an electrolyte additive. Since the conductivity of DEA is much lower than that of sodium hydroxide, a stable baseline and a 3-5 times improvement in separation efficiency was observed at a pH as high as 12.6. It was found that DEA reduced the electrophoretic mobility of carbohydrates by formation of ion-pairs, and also reduced the electroosmotic flow by masking the silanol groups at the capillary surface. Many monosaccharides, including glucose, rhamnose, mannose, and fructose, which have very similar pKa values, were completely separated using 5% DEA at pH 12.6. The separation of di- and trisaccharides using indirect detection with a borate buffer at pH 9.5 was also investigated. The separation of disaccharides was greatly improved with borate complexation using riboflavin as a background electrolyte (BGE) over the sodium hydroxide and DEA electrolyte system with sorbic acid as BGE. The resolution of carbohydrates increased as pH increased, and sucrose, trehalose, raffinose, and maltotriose were successfully separated at pH 11.8.

Boric Acids↗
PubMed2004

External reversible control of recognition behavior of alpha-peptide ribonucleic acid (alpha-PRNA) through anti-syn orientational switching of the nucleobase induced by borate esterification of the cis-2',3'-diol.

A novel nucleic acid model using peptide ribonucleic acid (PRNA), which contains 5'-amino-5'-deoxypyrimidine ribonucleoside as a recognition site for nucleic acids, has been designed, synthesized and applied to the external reversible control of recognition behavior of the complementary polynucleotide through the orientational switching of the nucleobase induced by borate.

Borates↗
PubMed2002

In vitro and in vivo dissolution behavior of a dysprosium lithium borate glass designed for the radiation synovectomy treatment of rheumatoid arthritis.

Dysprosium lithium borate (DyLB) glass microspheres were investigated for use in the radiation synovectomy treatment of rheumatoid arthritis. In vitro testing focused on weight loss and cation dissolution from glass microspheres immersed in simulated synovial fluid (SSF) at 37 degrees C for up to 64 days. In vivo testing was performed by injecting glass microspheres into the stifle joints of Sprague-Dawley rats and monitoring the biodegradability of the microspheres and the tissue response within the joints. The DyLB microspheres reacted nonuniformly in SSF with the majority of lithium and boron being dissolved, whereas nearly all of the dysprosium (>99.7%) remained in the reacted microspheres. Because the DyLB glasses released negligible amounts of dysprosium while reacting with SSF, they are considered safe for radiation synovectomy from the standpoint of unwanted radiation release from the joint capsule. Furthermore, the DyLB microspheres fragmented, degraded, and reacted with body fluids while in the joints of rats without histologic evidence of joint damage.

Algorithms↗
PubMed1986

Identification of N-acetylhexosamines produced by enzymes of the N-acetylneuraminic acid metabolic pathway by borate complex anion-exchange chromatography of the corresponding N-acetylhexosaminitols.

A mixture of hexosaminitols obtained by reducing N-acetylglucosamine, N-acetylgalactosamine, and N-acetylmannosamine with sodium borohydride was resolved by borate complex anion-exchange chromatography. This procedure yielded a complete separation of N-acetylglucosaminitol, N-acetylgalactosaminitol, and N-acetylmannosaminitol and provided a rapid and accurate means for identifying and measuring N-acetylhexosamines in biological samples. This method was applied to studies on N-acetylneuraminic acid metabolism in human skin fibroblasts. It was used to identify reaction products in two enzymatic reactions: the conversion of UDP-N-acetylglucosamine to N-acetylmannosamine and UDP by UDP-N-acetylglucosamine 2-epimerase and the conversion of N-acetylneuraminic acid to N-acetylmannosamine and pyruvate by N-acetylneuraminate pyruvate-lyase. It was also used to identify the free 3H-labeled N-acetylhexosamines found in fibroblasts cultured in the presence of N-[3H]acetylmannosamine.

Borates↗
PubMed1982

Equilibrium binding of amphotericin B and its methyl ester and borate complex to sterols.

Scatchard analysis of the binding of amphotericin B to sterols in egg phosphatidylcholine/sterol vesicles revealed that amphotericin B was bound to ergosterol by approximately one order of magnitude more tightly than to cholesterol. Amphotericin B methyl ester formed a tighter complex with each of the sterols investigated than did amphotericin B, but the difference in the apparent binding constants towards ergosterol and cholesterol was not as large as with amphotericin B. Amphotericin B borate formed weaker complexes with vesicle-bound sterols than amphotericin B and amphotericin B methyl ester.

Amphotericin B↗
PubMed1993

Borate complexation of flavonoid-O-glycosides in capillary electrophoresis. II. Separation of flavonoid-3-O-glycosides differing in their sugar moiety.

Capillary electrophoresis was found to give significantly higher efficiency, selectivity and speed than high-performance liquid chromatography for the separation of a mixture of flavonoid-3-O-glycosides differing in their sugar moiety. Boric acid running buffer (0.2 M, pH 10.5) was used for this electrophoretic separation. The migration order in free solution capillary electrophoresis (CE) and the selectivity of these flavonoid-3-O-glycosides can be mainly explained by in situ borate complexation of both the sugar moiety and the cis-1,2-hydroxyl groups on the flavonoid skeleton and, to a lesser extent, by the ionization of hydroxyl groups on the flavonoid skeleton due to alkaline pH conditions. The correlation of the electrophoretic mobilities with the configuration and conformation of the compounds is discussed.

Anions↗
PubMed1987

Pharmacological comparison of L-serine borate and glutathione as inhibitors of metabolism of LTC4 to LTD4 by the isolated guinea pig trachea.

Cumulative dose-response curves to leukotriene C4 (LTC4) and leukotriene D4 (LTD)4 were obtained on indomethacin (5 microM) treated isolated guinea pig tracheal spiral strips. LTC4 curves, in the presence of either glutathione (GSH; 10 mM) or L-serine borate (SB; 45 mM), were not antagonized by FPL-55712 (3 microM), a selective LTD4 receptor antagonist. LTC4 curves on trachea treated with a lower concentration of GSH (1 mM), and LTD4 curves were competitively antagonized by FPL-55712. LTC4 curves on GSH (10 mM) treated trachea were 2 fold to the left of those on SB treated tissues. This effect of GSH was blocked by pretreatment with nordihydroguiaretic acid (30 microM), an inhibitor of 5-lipoxygenase. GSH (10 mM) and SB (45 mM) are effective inhibitors of conversion of LTC4 into functionally important levels of LTD4 by the guinea pig trachea. In addition, GSH appears to enhance LTC4 responsiveness by increasing synthesis of a contractile 5-lipoxygenase product(s), possibly LTC4. From the data it is suggested that for inhibition of LTC4 metabolism, SB may be more useful when examining responses to exogenously applied LTC4, while GSH (10 mM) may be more useful when examining responses to endogenously generated LTC4.

Animals↗
PubMed1988

Analysis of IgG glycopeptides by alkaline borate gel filtration chromatography.

A protocol for the characterization of IgG glycopeptides is described. Central to this scheme is the novel application of an alkaline borate buffer to gel filtration chromatography. The use of this buffer significantly enhances the resolution of glycopeptides. Furthermore, it results in the separation of a unique size class of glycopeptides derived from IgG secreted by murine hybridomas. Although predominantly neutral, these glycopeptides differ both qualitatively and quantitatively by lectin affinity chromatography from the other glycopeptides which are presumably derived from the Fc portion of IgG.

Borates↗
PubMed1982

Effects of extended peroral borate ingestion on rat liver and brain.

2-Month-old male Wistar rats were given sodium tetraborate in drinking water (3 g/l). Cerebral succinate dehydrogenase activity increased after 10 and 14 weeks of exposure. Increased RNA concentration and increased acid proteinase activity in brain occurred after 14 weeks. NADPH-cytochrome c reductase activity and cytochrome b5 content decreased in the liver microsomal fraction after 10 and 14 weeks. A reduction in the cytochrome P-450 concentration was detected at 14 weeks. The results support the hypothesis that borate anion exerts its toxic action by interfering with flavin metabolism in flavoprotein-dependent pathways.

Administration, Oral↗