Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Magnesium Compounds”

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 289 records · Page 16Linked to original sources
PubMedDate not supplied

In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin.

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption.

Aluminum Compounds↗
PubMed2005

Electron-transfer mechanism in radical-scavenging reactions by a vitamin E model in a protic medium.

The scavenging reaction of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH.) or galvinoxyl radical (GO.) by a vitamin E model, 2,2,5,7,8-pentamethylchroman-6-ol (1H), was significantly accelerated by the presence of Mg(ClO4)2 in de-aerated methanol (MeOH). Such an acceleration indicates that the radical-scavenging reaction of 1H in MeOH proceeds via an electron transfer from 1H to the radical, followed by a proton transfer, rather than the one-step hydrogen atom transfer which has been observed in acetonitrile (MeCN). A significant negative shift of the one-electron oxidation potential of 1H in MeOH (0.63 V vs. SCE), due to strong solvation as compared to that in MeCN (0.97 V vs. SCE), may result in change of the radical-scavenging mechanisms between protic and aprotic media.

Benzhydryl Compounds↗
PubMed2001

Calcium sensitization produced by G protein activation in airway smooth muscle.

We determined whether activation of G proteins can affect the force developed for a given intracellular Ca(2+) concentration ([Ca(2+)]; i.e., the Ca(2+) sensitivity) by mechanisms in addition to changes in regulatory myosin light chain (rMLC) phosphorylation. Responses in alpha-toxin-permeabilized canine tracheal smooth muscle were determined with Ca(2+) alone or in the presence of ACh, endothelin-1 (ET-1), or aluminum fluoride (AlF; acute or 1-h exposure). Acute exposure to each compound increased Ca(2+) sensitivity without changing the response to high [Ca(2+)] (maximal force). However, chronic exposure to AlF, but not to chronic ACh or ET-1, increased maximal force by increasing the force produced for a given rMLC phosphorylation. Studies employing thiophosphorylation of rMLC showed that the increase in force produced by chronic AlF exposure required Ca(2+) during activation to be manifest. Unlike the acute response to receptor agonists, which is mediated solely by increases in rMLC phosphorylation, chronic direct activation of G proteins further increases Ca(2+) sensitivity in airways by additional mechanisms that are independent of rMLC phosphorylation.

Acetylcholine↗
PubMed1998

Investigation of foreign substances in food using scanning electron microscopy-x-ray microanalysis.

Scanning electron microscopy (SEM) and x-ray microanalysis (EDS) were used to conduct forensic investigations on metal and glass foreign objects. SEM-EDS is an excellent method for identifying metal foreign objects in food, such as wire, dental fillings, bone, and metal packaging, based on their element composition. From a determination of the extent of corrosion of a metal foreign object using SEM-EDS, it is sometimes possible to determine whether the material has been processed with the food product. Case histories of processed aluminum, unprocessed nickel-coated steel, and corrosion resistant stainless steel foreign objects are discussed. A potential product-tampering problem involving a hole defect in a paperboard package was resolved using SEM-EDS. Blue fibers found in the hole were found to contain brass particles from a ball point pen rather than a syringe needle. SEM-EDS has been used to determine the elemental composition of glass foreign objects and is able to distinguish between many types of glass including container, electrical, and bakeware. A case history is presented to show that although container glasses cannot, in general, be distinguished from one another using SEM-EDS, they can be distinguished by trace element semiquantitative spectrograghic analysis. SEM-EDS can be used to distinguish glass-like foreign objects from glass. Case histories of struvite crystals found in salmon and cream of tartar crystals found in grape juice are discussed. Fourier transform infrared (FTIR) identified the cream of tartar crystal as calcium tartrate, and this complemented the calcium, carbon, and oxygen components of the compound found using SEM-EDS.

Animals↗
PubMed1986

Comparative pathological aspects of chronic olivine and silica inhalation in mice.

A comparative study was done in mice on the effects of silica and olivine inhalation. The exposure periods in the dust chambers were for periods of 150, 300, and 570 days, with the longest time period covering a large portion of the predicted life span of the Balb/c mouse. Detailed necropsies including histology were done at the end of the exposures and at 30 and 150 days following removal of animals from the 150- and 300-day dust exposures. The results indicate that silica causes considerably more tissue damage in lungs and mediastinal lymph nodes, leading to granulomas.

Animals↗
PubMedDate not supplied

A comparative bioavailability study to estimate the influence of an antacid on droxicam pharmacokinetics.

The influence of an antacid on droxicam pharmacokinetics was investigated in 12 healthy male volunteers. A two way cross-over study was performed after the oral administration of 20 mg of droxicam (Ombolan capsules) and droxicam together with an antacid (Mucal powder). The plasma concentrations of piroxicam, the active moiety of droxicam, were determined by a high-performance liquid chromatographic method. The pharmacokinetic parameter values (mean +/- RSD) of piroxicam after administration of droxicam alone were: AUC0-->infinity = 125.5 +/- 25.1 micrograms.h/l, Cmax = 2.08 +/- 19.9 micrograms/l, tmax = 7.08 +/- 36.8 h and t1/2 = 46.3 +/- 27.0 h. Following administration of droxicam together with the antacid the values obtained for the same parameters were: AUC0-->infinity = 135.1 +/- 24.1 micrograms.h/l. Cmax = 1.85 +/- 23.9 micrograms/l, tmax = 8.17 +/- 34.9 h and t1/2 = 52.0 +/- 22.4 h. These results indicate that concurrent administration of the antacid does not significantly change the bioavailability and pharmacokinetics of droxicam.

Administration, Oral↗
PubMed1986

The ability of antacids and cholestyramine to bind bile acids: effect of pH.

Reflux of bile into the stomach may be injurious to the gastric mucosa. The ability of antacids and cholestyramine to bind bile acids is therefore potentially valuable in the treatment of reflux gastritis. The ability of antacids and cholestyramine to remove bile acids from gastric juice, hepatic bile, and solutions of commercially available bile acids was investigated in vitro over a pH range likely to occur in the stomach. The percentage of bile acids removed by antacids decreased with decreasing initial bile acid concentration and usually decreased as the incubation pH was increased from 3.6 to 7.0. Glycine-conjugated bile acids were bound to a greater extent than taurine-conjugated bile acids and dihydroxy to a greater extent than trihydroxy bile acids. Cholestyramine bound 97-100% of all bile acids in solution at pH 3.6 and pH 7.0. The effect of pH on adsorption should therefore be considered when antacids are used to treat gastritis.

Aluminum Compounds↗
PubMed1990

A simple technique for studying struvite crystal growth in vitro.

Struvite urolithiasis forms as a consequence of a urinary tract infection by urease-producing species of bacteria such as Proteus mirabilis. Ammonia, produced by the enzymatic hydrolysis of urea, elevates urine pH causing a supersaturation and precipitation of Mg++ as struvite (NH4MgPO4). Calcium often precipitates as well, forming the mineral carbonate-apatite (Ca10(PO4)6CO3). We have developed a procedure based on direct observation by light microscopy whereby struvite crystal growth can be quickly monitored in response to chemical changes in urine. As struvite crystals assume a characteristic shape or crystal habit based on their growth rate, the effect of urine chemistry and the action of various crystallization or urease inhibitors on struvite formation can be quickly shown. In addition preliminary effects of alkaline pH, or the presence of toxic compounds on bacteria can also be shown through their loss of motility.

Crystallization↗
PubMed2005

Integral water treatment plant modeling: improvements for particle processes.

An update of research on particle behavior in water treatment plants first performed 25 years ago under the direction of Charles O'Melia is provided. The earlier work involved mathematical modeling of the changes in particle size distributions in the flocculation and sedimentation processes in water treatment plants. The current model includes corrections for short-range interactions between particles as they approach one another. These corrections severely reduce the expected collision frequency between particles that are very different in size and, therefore, substantially change the model predictions. Both experimental and field measurements of particle size distributions are provided; such measurements were unavailable in the earlier work and represent a touchstone to reality for the modeling efforts. The short-range model successfully fits experimental results for flocculation when the mechanism of particle destabilization is charge neutralization. However, the model does not account for the creation of new solids by precipitation either when hydrolyzing salts of aluminum or iron are added for particle destabilization by "sweep floc" destabilization or lime is added to remove calcium and magnesium as calcium carbonate and magnesium hydroxide in softening. The flocculent sedimentation model yields results that are in strong qualitative agreement with typical field measurements.

Aluminum Compounds↗
PubMed2001

Simultaneous accumulation of calcium, phosphorus, and magnesium in various human arteries.

To elucidate compositional changes of the arteries with aging, the authors investigated the relationships among average contents of calcium, phosphorus, sulfur, and magnesium in the arteries by inductively coupled plasma-atomic emission spectrometry. The arteries used were the thoracic and abdominal aortas, coronary, common carotid, anterior, middle and posterior cerebral, vertebral, basilar, internal thoracic, axillary, radial, truncus celiacus, common, internal and external iliac, femoral, popliteal, and umbilical arteries. It was found that high correlations were found between the average contents of calcium and phosphorus, between the average contents of calcium and magnesium, and between the average contents of phosphorus and magnesium in the arteries, but not between the average contents of sulfur and the other elements. These correlations revealed that as the content of calcium and phosphorus increased in the arteries, the magnesium content increased simultaneously in the arteries, but the sulfur content did not. It is likely that magnesium forms compounds with phosphorus in the arteries.

Adult↗
PubMed1993

[Struvite calculi dietetics: 2. Effect of ammonium chloride and carbonates on the acid-base and mineral balance of cats].

Six healthy adult cats were fed a basal minced beef meat and rice diet with varying amounts or combinations of acidifying and alkalizing additives (ammonium chloride, calcium and sodium carbonate). The base excess in the food (mmol/kg dry matter) was calculated (data on food compounds in g/kg dry matter) as follows: base excess = 49.9*Ca + 82.3*Mg + 43.5*Na + 25.6*K - 64.6*P - 13.4*Met-16.6*Cystine -28.2*Cl. It amounted to between +305 and -1079 mmol/kg dry matter. Urine and blood pH as well as balance of minerals and water were determined in the cats. The mean urine pH ranged between 6.1 and 7.8. There was a highly significant correlation between the base excess in the food and the mean urine pH. The regression line was linear down to a base excess in the diet of about -400 to -500 mmol/kg dry matter and a pH in the urine of 6.2. The postprandial increase of urine pH was suppressed either by large amounts of ammonium chloride (> 780 mmol/kg dry matter) alone or in combination with calcium carbonate, but not in combination with sodium carbonate. The relationship between the decrease of the blood pH and the amount of ammonium chloride added to the diet was more marked than the relationship between blood pH and base excess in the food. In order to avoid health risks by long term application of acidifying diets it is recommended to formulate struvite diets with low base excess in such a way, that they contain as few alkalizing compounds as possible, which must be neutralized by acidifiers.

Acid-Base Equilibrium↗
PubMed2000

[Studies of adsorbents for hemoperfusion--preparation and in vitro studies of cross-linked agar beads entrapped Attapulgite clay].

A new method for preparation of cross-linked agar beads entrapped Attapulgite clay (CAA) is reported. Attapulgite clay was coated with agar and shaped in organic solvent, as well as cross-linked by epichlorohydrin. The products withstood autoclaving at 121 degrees C for 30 minutes and had a good adsorption ability for model compounds and medicines. The results of preliminary investigation indicate that CAA is relatively hemocompatible.

Adsorption↗
PubMed2005

Formation and morphology of struvite and newberyite in aqueous solutions at 25 and 37 degrees C.

The influence of the initial reactant concentrations (c(i)(Mg)tot = 5.0 x 10(6) to 5.0 x 10(-1) mol dm(-3), c(i)(P)tot = c(i)(NH4)tot = 1.0 x 10(-3) to 5.0 x 10(-1) mol dm(-3)) and temperature (25 and 37 degrees C) on the composition and morphology of the precipitates formed in the system MgCl2-NH4H2PO4-NaOH-H2O at initial pHi = 7.40 has been investigated. Precipitation diagrams are presented showing the concentration regions within which different morphologies of solid phase have been formed. The solid phases aged for 24 hours were characterized by means of optical microscopy, FT-IR spectrophotometry, X-ray diffractometry and thermogravimetry. It was found that struvite was a predominant phase formed within the concentration region examined and newberyite was obtained only in the region where pH(24h) < 6.5. The influence of the initial pH on the formation and transformation of these two compounds were studied in the region 5.0 < or = pHi < or = 9.0 and the results are discussed.

Chemical Precipitation↗
PubMed2006

Modification of clay barriers with a cationic surfactant to improve the retention of pesticides in soils.

In this work, the efficiency of reactive clay barriers in the immobilisation of organic pesticides in a sandy soil was studied. Reactive barriers were prepared by modification of montmorillonite, kaolinite and palygorskite clay minerals, and of a clayey soil with the cationic surfactant octadecyltrimethylammonium bromide (ODTMA). Percolation curves of the pesticides linuron, atrazine and metalaxyl of different hydrophobic character, were obtained in columns packed with a natural sandy soil with these barriers intercalated under saturated flow conditions. The cumulative curves in the unmodified soil indicated a leaching of pesticides greater than 85% of the total amount of compound added. After barrier intercalation, the breakthrough curves (BTC) indicated a dramatic decrease in the amounts of linuron leached in all columns and a significant modification of the leaching kinetics of atrazine and metalaxyl. Retardation factors, R, of the pesticides in the columns were significantly correlated with the organic matter content (OM) derived from the ODTMA of the organo clay/soil barriers (r2>or=0.78). Significant correlations were also found between these R factors and the pore volume values corresponding to the maximum peaks of the BTCs (r2=0.83; p<0.01) or the total volumes leached (r2=0.44; p<0.05) for the pesticides atrazine and metalaxyl. The results obtained point to the interest in the use of reactive clay barriers for almost complete immobilisation of hydrophobic pesticides or for decreasing the leaching of moderately hydrophobic pesticides coming from point-like sources of pollution. These barriers would avoid the generation of elevated concentrations of these compounds in the soils due to their rapid washing.

Aluminum Silicates↗
PubMed2001

Accumulation of magnesium as well as calcium and phosphorus in Japanese monkey arteries with aging.

To examine whether an accumulation of elements in the arteries with aging differs between human and animal, the authors investigated the relationships among element contents in the arteries of the Japanese monkeys. The Japanese monkeys consisted of five males and four females, ranging in age from 2 to 29 yr. The aorta, common and external iliac, femoral, common carotid, subclavian, and axillary arteries were resected from the monkeys and element contents were determined by inductively coupled plasma-atomic emission spectrometry. It was found that there were very high correlations between calcium and phosphorus contents, between calcium and magnesium contents, and between phosphorus and magnesium contents in all of the monkey arteries. In addition, significant correlations were found among the other element contents in some, but not all of the arteries. These results were consistent with the foregoing findings of the human arteries. It is likely that magnesium forms compounds with phosphorus or calcium in the monkey arteries.

Age Factors↗
PubMed1994

An in vitro study of the effects of different crystal growth solutions on the topography of the enamel surface.

This study evaluated the effect on the topography of the enamel surface of applying various solutions based on polyacrylic acid. This base solution consisted of 50 per cent aqueous polyacrylic acid (molecular weight 5000) and concentrated sulphuric acid (98 per cent). Previously, similar solutions have been found to initiate a crystal growth on the enamel surface and have been proposed as being suitable for the attachment of orthodontic brackets via a composite resin interface. The base solution was modified by the addition of various ionic salts: the sulphates of lithium, magnesium and potassium, respectively. Human premolar teeth were then treated to a standard format and the effect on the enamel surface was examined by the use of a scanning electron microscope at x 500 and x 1500 magnification. The resultant micrographs of the specimens were presented to three independent observers who assessed the length, quality, and degree of coverage of the crystals. The solution containing potassium sulphate gave the longest crystals, whilst the greatest degree of coverage was obtained with the magnesium sulphate solution. Each solution was found to produce a consistent and recognizable morphology.

Acid Etching, Dental↗