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PubMed2006

Effects of the supporting electrolyte on the kinetics of the removal of proteins adsorbed on a stainless steel surface by H2O2-electrolysis.

The effects of different types of supporting electrolytes on the removal of beta-lactoglobulin (beta-Lg) after being adsorbed to a stainless steel surface by a H2O2-electrolysis treatment was investigated. In this process, hydroxyl radicals (*OH), generated by the electrolysis of hydrogen peroxide, decompose the substances adhering to the surface. The removal of the adsorbed protein from the stainless steel surface during the treatment was monitored in situ by ellipsometry. The apparent first-order removal rate constants, k(cl), for 17 types of supporting electrolytes were determined, as well as the current corresponding to the rate of generation of *OH. The k(cl) and generated current values for LiCl, NaCl, KCl, KNO(3), K(2)SO(4), CH(3)COOK, and K(2)CO(3) were all similar. Ca(2+) and Mg(2+) strongly suppressed the removal of the adsorbed protein. The presence of ammonium compounds led to an increase in k(cl) and current values. In H2O2-electrolysis in the presence of potassium phosphate, the removal was extremely rapid, and an apparent increase in the thickness of the adsorbed layer was observed. The mechanisms responsible for the peculiar effects of calcium, magnesium, phosphate, and ammonium compounds were investigated by means of a Fourier transform infrared (FTIR) spectroscopic analysis, as well as by the characteristics of the removal under different treatment conditions.

Electrolytes↗
PubMed2002

Purification and characterization of isocitrate lyase from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose.

Isocitrate lyase (EC 4.1.3.1), a key enzyme in the glyoxylate cycle, was purified 76-fold with 23% yield as an electrophoretically homogeneous protein from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose. The native enzyme has a molecular mass of 186 kDa, consisting of three identical subunits of 60 kDa. The K(m) for DL-isocitrate was found to be 1.6 mM at the optimum pH (7.0). The enzyme required Mg(2+) (K(m) 92 microM) and sulfhydryl compounds for optimal activity. The enzyme activity was strongly inhibited by oxalate and itaconate with a K(i) of 37 and 68 microM, respectively. The inhibition by the glycolysis and tricarboxylic acid cycle intermediates and related compounds suggested that the isocitrate lyase was a regulatory enzyme playing a crucial role in the fungal growth.

Basidiomycota↗
PubMed1995

Confirmation that magnesium lithospermate B has a hydroxyl radical-scavenging action.

Male LWH: Wistar rats were given creatinine (Cr) intraperitoneally at a dose of 1.00 g/kg body weight, and the urine was collected for 3 h after administration. Magnesium lithospermate B, a compound newly isolated from Salviae Miltiorrhizae Radix, was administered intraperitoneally 30 min before and 30 min after Cr administration. The excretion of urinary creatol and methylguanidine induced by Cr decreased in a dose-dependent manner. Since we have already shown that the main contributor to the Cr-->creatol oxidation step is the hydroxyl radical, magnesium lithospermate B may act as a radical scavenger.

Animals↗
PubMed1993

Magnesium bioavailability from human milk, cow milk, and infant formula in suckling rat pups.

Little is known about the absorption of magnesium from infant diets. Magnesium bioavailability was evaluated from infant diets that varied by protein and carbohydrate source; magnesium, calcium, and phosphorus contents; and the form of magnesium fortification. Diets were separated into soluble, insoluble, and fat fractions to determine magnesium distribution. Most of the magnesium (> 62%) was found in the soluble fraction. Gel filtration of the soluble fraction from all diets studied showed that > 95% of magnesium is free or associated with low-molecular-weight compounds. Distribution of 28Mg and native magnesium in fractions of the diets was similar, thus validating the use of an extrinsic label. In vitro digestion decreased the percent insoluble magnesium from as high as 35% to 2-8%. Whole-body retention of 28Mg-labeled diets in suckling rat pups 4 h after oral intubation ranged from 51% to 92%. No significant differences were found between human milk, cow milk, and infant formula. In conclusion, magnesium from the infant diets studied has high bioavailability, and moderate differences in their composition do not affect bioavailability significantly.

Animals↗
PubMed1992

Cholinergic interneurons in the feeding system of the pond snail Lymnaea stagnalis. II. N1 interneurons make cholinergic synapses with feeding motoneurons.

The N1 neurons are a population of interneurons active during the protraction phase of the feeding rhythm. All the N1 neurons are coupled by electrical synapses which persist in a high Mg/low Ca saline which blocks chemical synapses. Individual N1 spikes produce discrete electrotonic postsynaptic potentials (PSPS) in other N1 cells, but the coupling is not strong enough to ensure 1:1 firing. Bursts of N1 spikes generate compound PSPS in the feeding motoneurons. The sign (excitation or inhibition) of the N1 input corresponds with the synaptic barrage recorded during the protraction phase. Discrete PSPS are only resolved in a Hi-Di saline. Their variation in latency and number can be explained by variation in electrotonic propagation within the electrically coupled network of N1 cells. The excitatory postsynaptic potentials (ESPS) in the 1 cell are reduced by 0.5 mM antagonists hexamethonium (HMT), atropine (ATR), curare (d-TC) and by methylxylocholine (MeXCh), all of which block the excitatory cholinergic receptor (Elliott et al. (Phil. Trans. R. Soc. Lond. 336, 157-166 (Preceding paper.) (1992)). The 1 cell EPSPS were transiently blocked by phenyltrimethylammonium (PTMA), which is both an agonist and antagonist at the 1 cell excitatory acetylcholine (ACh) receptor (Elliott et al. 1992). The inhibitory postsynaptic potential (IPSP) in the 3 cell is blocked by bath applications of MeXCh and PTMA, which both abolish the response of the 3 cell to ACh (Elliott et. al. 1992). The effects of the cholinergic antagonists on the response of 4 cluster and 5 cells to N1 stimulation matches their response to ACh (Elliott et al. 1992). It is concluded that the population of N1 cells are multiaction, premotor cholinergic interneurons.

Acetylcholine↗
PubMed1982

Metal binding by pharmaceuticals. Part 2. Interactions of Ca(II), Cu(II), Fe(II), Mg(II), Mn(II) and Zn(II) with the intracellular hydrolysis products of the antitumour agent ICRF 159 and its inactive homologue ICRF 192.

Formation constants for the calcium(II), copper(II), iron(II), magnesium(II), manganese(II) and zinc(II) complexes of dl-NN'-dicarboxamidomethyl-NN'-dicarboxymethyl-1,2-diaminopropane (ICRF 198) and the 1,2-diamino-butane homologue (ICRF 226) have been measured potentiometrically at 37 degrees C and I=150 mmol dm-3 [NaCl]. The constants are used in computer simulation models to assess the relative avidity of these compounds for biologically essential metal ions in vivo. It is shown that the agents interact similarly with all of the ions studied except those of zinc(II), which are particularly strongly chelated by the hydrolysis product of ICRF 192. This effect could be responsible for the difference in cytotoxicity exhibited by the antitumour agent ICRF 159 (Razoxane) and its inactive homologue ICRF 192. However, the mechanism through which this might occur remains unclear.

Antineoplastic Agents↗
PubMed1995

The effect of the desglycinyl metabolite of remacemide on cortical wedges prepared from DBA/2 mice.

Remacemide hydrochloride is currently undergoing clinical trials for use as an anticonvulsant agent in the treatment of epilepsy. It is considered that the desglycinyl metabolite (FPL 12495AA) of the parent compound accounts for the majority of the anticonvulsant activity. In this study we have investigated the effects of FPL 12495AA on electrical activity in the cortical wedges prepared from audiogenic seizure-prone DBA/2 mice. FPL 12495AA at varying concentrations (50-200 microM) significantly reduced both the spontaneous depolarizations (IC50 102 microM) and the associated afterpotentials (IC50 50 microM) which are characteristic in this preparation under magnesium-free conditions. The compound also concentration-dependently reduced N-methyl-D-aspartate (NMDA)-induced depolarizations of the tissue (IC50 43 microM) and the antagonism by FPL 12494AA was not overcome by increasing NMDA concentrations. FPL 12495AA had no effect on (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)-induced depolarizations. The results suggest that FPL 12495AA has a specific antagonistic effect on the NMDA receptor complex possibly through non-competitive inhibition at the phenycyclidine site in the ion channel. Such an action could contribute to its anticonvulsant properties.

Acetamides↗
PubMed2001

Magnesium inhibits arterial thrombi after vascular injury in rat: in vivo impairment of coagulation.

Magnesium deficiency is associated with a high frequency of cardiac arrhythmia, hypertension and sudden ischemic death. We investigated the if vivo effects of intravenous magnesium administration in a rat model of chemically induced (FeCl3) carotid thrombosis. The infusion of magnesium sulfate (MgSO4) before the topical application of FeCl5 prevented thrombus formation at concentrations of 0.3 M and 0.6 M, and delayed it even at 0.15 M. Similar results were obtained with MgCl2. The infusion of MgSO4 0.6 M seven minutes after FeCl3 application delayed but did not prevent thrombus formation. MgSO4 slightly reduced platelet aggregation ex vivo without affecting plasma clotting tests, but in vivo blood clotting time was markedly prolonged (tail transection method), thus indicating profoundly impaired coagulation. These data provide a rationale for the use of magnesium as an antithrombotic agent. but its pharmacological effect critically depends on the timing of administration.

Animals↗
PubMed1992

Bovine inositol monophosphatase: development of a continuous fluorescence assay of enzyme activity.

This paper describes a continuous assay for the enzyme inositol monophosphatase which has been developed using a new substrate, the fluorescent compound 4-methylumbelliferyl phosphate. The hydrolysis of the phosphate group from this compound can be readily detected by a resultant large red shift in the emission spectrum from 390-450 nm. The kinetic constants for the enzyme using this new substrate are described.

Animals↗
PubMed1975

Ribulose diphosphate carboxylase/oxygenase. IV. Regulation by phosphate esters.

The stimulation or inhibition of ribulose diphosphate oxygenase by a variety of compounds is compared with the reported effects on these compounds on the ribulose diphosphate carboxylase activity. A possible transition state analog of ribulose diphosphate, 2-carboxyribitol 1, 5-diphosphate, at a molar ratio of inhibitor to enzyme of 10 to 1, irreversibly inactivates the oxygenase and carboxylase activities. This is consistent with the hypothesis that there may be a single active site for both the carboxylase and oxygenase activities. Several compounds of the reductive pentose photosynthetic carbon cycle act as effectors of the ribulose diphosphate oxygenase in a manner complementary to their reported effect upon the carboxylase. Ribose 5-phosphate inhibits the oxygenase with an apparent Ki of 1.8 mM, but it is reported to activate the carboxylase; fructose 6-phosphate and glucose 6-phosphate act similarly but are less effective than ribose 5-phosphate. Fructose 1. 6-diphosphate stimulates the oxygenase at low magnesium ion concentrations. The stimulatory effect of 6-phosphogluconate on the oxygenase is associated with a 3-fold reduction of the Km (Mg2+). ATP inhibits the oxygenase but has been reported to stimulate the carboxylase; pyrophosphate acts in an opposite manner. From these results it appears that the ratio of carboxylase to oxygenase activity may be a variable factor with predictable subsequent alteration in the ratio between photosynthetic CO2 fixation and photorespiration.

Adenosine Triphosphate↗
PubMed1994

The preservation of some oral liquid preparations. The replacement of chloroform by other preservatives.

Chloroform should be considered as an obsolete preservative for pharmaceutical preparations, because of its toxicological implications and its physical instability. The effectiveness of possible alternatives for chloroform in three oral liquid pharmaceutical preparations was investigated, using a microbiological challenge test. Magnesium trisilicate mixture (British Pharmacopoeia) can be adequately preserved with methylparaben (2 g/l). Only insignificant amounts of methylparaben were absorbed by the solids present in the magnesium trisilicate mixture. Ferrous sulfate mixture (British Pharmacopoeia) can be preserved with a mixture of methylparaben (1.8 g/l) and propylparaben (0.2 g/l). Sorbic acid (1 g/l) is a suitable preservative for promethazine hydrochloride syrup.

Administration, Oral↗
PubMed2004

Citric acid production by selected mutants of Aspergillus niger from cane molasses.

The present investigation deals with citric acid production by some selected mutant strains of Aspergillus niger from cane molasses in 250 ml Erlenmeyer flasks. For this purpose, a conidial suspension of A. niger GCB-75, which produced 31.1 g/l citric acid from 15% (w/v) molasses sugar, was subjected to UV-induced mutagenesis. Among the 3 variants, GCM-45 was found to be a better producer of citric acid (50.0 +/- 2a) and it was further improved by chemical mutagenesis using N-methyl, N-nitro-N-nitroso-guanidine (MNNG). Out of 3,2-deoxy-D-glucose resistant variants, GCMC-7 was selected as the best mutant, which produced 96.1 +/- 1.5 g/l citric acid 168 h after fermentation of potassium ferrocyanide and H2SO4 pre-treated blackstrap molasses in Vogel's medium. On the basis of kinetic parameters such as volumetric substrate uptake rate (Qs), and specific substrate uptake rate (qs), the volumetric productivity, theoretical yield and specific product formation rate, it was observed that the mutants were faster growing organisms and produced more citric acid. The mutant GCMC-7 has greater commercial potential than the parental strain with regard to citrate synthase activity. The addition of 2.0 x 10(-5) M MgSO4 x 5H2O into the fermentation medium reduced the Fe2+ ion concentration by counter-acting its deleterious effect on mycelial growth. The magnesium ions also induced a loose-pelleted form of growth (0.6 mm, diameter), reduced the biomass concentration (12.5 g/l) and increased the volumetric productivity of citric acid monohydrate (113.6 +/- 5 g/l).

Aspergillus niger↗
PubMed2004

Porphyrins bearing arylphosphonic acid tethers for attachment to oxide surfaces.

Synthetic molecules bearing phosphonic acid groups can be readily attached to oxide surfaces. As part of a program in molecular-based information storage, we have developed routes for the synthesis of diverse porphyrinic compounds bearing phenylphosphonic acid tethers. The routes enable (1) incorporation of masked phosphonic acid groups in precursors for use in the rational synthesis of porphyrinic compounds and (2) derivatization of porphyrins with masked phosphonic acid groups. The precursors include dipyrromethanes, monoacyldipyrromethanes, and diacyldipyrromethanes. The tert-butyl group has been used to mask the dihydroxyphosphoryl substituent. The di-tert-butyloxyphosphoryl unit is stable to the range of conditions employed in syntheses of porphyrins and multiporphyrin arrays yet can be deprotected under mild conditions (TMS-Cl/TEA or TMS-Br/TEA in refluxing CHCl(3)) that do not cause demetalation of zinc or magnesium porphyrins. The porphyrinic compounds that have been prepared include (1) A(3)B-, trans-AB(2)C-, and ABCD-porphyrins that bear a single phenylphosphonic acid group, (2) a trans-A(2)B(2)-porphyrin bearing two phenylphosphonic acid groups, (3) a chlorin that bears a single phenylphosphonic acid group, and (4) a porphyrin dyad bearing a single phenylphosphonic acid group. For selected porphyrin-phosphonic acids, the electrochemical characteristics have been investigated for molecules tethered to SiO(2) surfaces grown on doped Si. The voltammetric behavior indicates that the porphyrin-phosphonic acids form robust, electrically well-behaved monolayers on the oxide surface.

Journal Article↗
PubMed1986

Identification of uroliths by infrared spectroscopy.

Wet chemical tests have deficiencies when applied to mixtures containing silica, which are common in the uroliths of some domestic animals. Consequently, the applicability of an infrared spectroscopic method was tested on 104 uroliths obtained from cattle, sheep, goats, horses, pigs, dogs, a chicken and a rabbit during diagnostic investigations. The following components were satisfactorily identified: silica, calcium oxalate, calcium carbonate, calcium phosphate, magnesium ammonium phosphate, magnesium phosphate and urates. The infrared characteristics of these compounds and their mixtures are described.

Animals↗