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 595 records · Page 33Linked to original sources
PubMed1993

Characterization of antacid compounds containing both aluminum and magnesium. II. Codried powders.

The composition and antacid properties of six samples of codried antacids containing both aluminum and magnesium were determined. Aluminum hydroxide-magnesium carbonate codried gel and aluminum hydroxide-magnesium hydroxide codried gel were non-homogeneous, as the samples contained combinations of hydrotalcite, amorphous aluminum hydroxide, magnesium hydroxide, magnesium hydroxycarbonate, and magnesium carbonate. All samples passed the preliminary antacid test and had high acid neutralizing capacities. However, the rate of acid neutralization varied between samples. In some cases the rate of acid neutralization at a dose of 400 mg was too slow to raise the pH to 3.0 as required by the Rossett-Rice test.

Aluminum↗
PubMed1999

The 2.0 A structure of human hypoxanthine-guanine phosphoribosyltransferase in complex with a transition-state analog inhibitor.

The structure of human HGPRT bound to the transition-state analog immucillinGP and Mg2+-pyrophosphate has been determined to 2.0 A resolution. ImmucillinGP was designed as a stable analog with the stereoelectronic features of the transition state. Bound inhibitor at the catalytic site indicates that the oxocarbenium ion of the transition state is stabilized by neighboring-group participation from MgPPi and O5'. A short hydrogen bond forms between Asp 137 and the purine ring analog. Two Mg2+ ions sandwich the pyrophosphate and contact both hydroxyls of the ribosyl analog. The transition-state analog is shielded from bulk solvent by a catalytic loop that moves approximately 25 A to cover the active site and becomes an ordered antiparallel beta-sheet.

Binding Sites↗
PubMed1987

Reduced glomerular filtration rate and hypercalciuria in primary struvite nephrolithiasis.

Struvite nephrolithiasis is caused by infection with bacteria that possess the enzyme urease, and convert urea to ammonia that raises urine pH and crystallizes with magnesium and trivalent phosphate ion. Of the 75 of our 1431 stone patients with struvite stones 52 were women. Struvite stones occurred almost exclusively in women; a minority of women and most men had mixed stones of struvite and calcium oxalate. Increased serum creatinine levels and reduced creatinine clearance were common in patients with struvite stones, not in those with mixed stones; both were rare in calcium stone disease. Men and women with mixed struvite, calcium oxalate stones were hypercalciuric, but women with struvite stones were not. Patients with mixed stones usually had initial symptoms of stone passage, and were less likely to need surgery, including nephrectomy, or to form contralateral stones. Patients with struvite stones usually presented with infection or no symptom, not passage. We conclude that struvite stones occur in two forms. The struvite stone is a disease of women, presumably occurring de novo from infection. The mixed stones occur in both sexes, presumably from secondary infection in hypercalciuric patients who begin with calcium-oxalate stone disease.

Blood Pressure↗
PubMed2004

Lumenal gating mechanism revealed in calcium pump crystal structures with phosphate analogues.

P-type ion transporting ATPases are ATP-powered ion pumps that establish ion concentration gradients across biological membranes. Transfer of bound cations to the lumenal or extracellular side occurs while the ATPase is phosphorylated. Here we report at 2.3 A resolution the structure of the calcium-ATPase of skeletal muscle sarcoplasmic reticulum, a representative P-type ATPase that is crystallized in the absence of Ca2+ but in the presence of magnesium fluoride, a stable phosphate analogue. This and other crystal structures determined previously provide atomic models for all four principal states in the reaction cycle. These structures show that the three cytoplasmic domains rearrange to move six out of ten transmembrane helices, thereby changing the affinity of the Ca2+-binding sites and the gating of the ion pathway. Release of ADP triggers the opening of the lumenal gate and release of phosphate its closure, effected mainly through movement of the A-domain, the actuator of transmembrane gates.

Adenosine Diphosphate↗
PubMed2003

Structural phase transition at the percolation threshold in epitaxial (La0.7Ca0.3MnO3)1-x:(MgO)x nanocomposite films.

'Colossal magnetoresistance' in perovskite manganites such as La0.7Ca0.3MnO3 (LCMO), is caused by the interplay of ferro-paramagnetic, metal-insulator and structural phase transitions. Moreover, different electronic phases can coexist on a very fine scale resulting in percolative electron transport. Here we report on (LCMO)1-x:(MgO)x (0 < x < or = 0.8) epitaxial nano-composite films in which the structure and magnetotransport properties of the manganite nanoclusters can be tuned by the tensile stress originating from the MgO second phase. With increasing x, the lattice of LCMO was found to expand, yielding a bulk tensile strain. The largest colossal magnetoresistance of 10(5)% was observed at the percolation threshold in the conductivity at xc 0.3, which is coupled to a structural phase transition from orthorhombic (0 < x < or 0.1) to rhombohedral R3c structure (0.33 < or = x < or = 0.8). An increase of the Curie temperature for the Rc phase was observed. These results may provide a general method for controlling the magnetotransport properties of manganite-based composite films by appropriate choice of the second phase.

Calcium Compounds↗
PubMed1981

Urolithiasis in patients with spinal cord injury.

The composition of the stone was determined in 24 paraplegic patients from whom 26 stones were surgically removed. Twenty-five of the 26 stones consisted of 90 per cent magnesium ammonium phosphate and 10 per cent carbonate apatite. The remaining single stone was composed of 90 per cent calcium oxalate and 10 per cent magnesium ammonium phosphate. Renal function improved significantly with the removal of the stones.

Adult↗
PubMed1998

Analytical control of wollastonite for biomedical applications by use of atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry.

Preliminary in vitro experiments revealed that wollastonite (CaSiO3) is a potentially highly bioactive material that forms a hyroxyapatite (HA) surface layer on exposure to simulated body fluid with an ion concentration, pH and temperature virtually identical with those of human blood plasma. The formation of the HA layer is an essential requirement for an artificial material to be used as bioactive bone substitute. This finding opens up a wide field for biomedical applications of wollastonite. Biomaterials used as implants in the human body require strict control of trace elements and of the toxic species specified in American Society for Testing and Materials F-1185-88 (As, Cd, Hg and Pb) in ceramic hydroxyapatite for surgical implantation. In this work, two types of pseudowollastonite, the high temperature form of wollastonite, were analysed by using cold vapour atomic absorption spectrometry and hydride generation atomic absorption spectrometry, in order to determine the elements stated in the above-mentioned norm, and inductively coupled plasma atomic emission spectrometry to establish the SiO2/CaO ratio of the two materials and analyse for all other impurities introduced by the raw materials and by the processes of synthesis, sintering and grinding. Barium and Mg were especially prominent in raw materials, and Zr, Y, Mg, W, Co and Ni come mainly from the processing.

Barium↗
PubMed1990

Determination of low-energy beta-emitter radionuclides deposited on surfaces by attapulgite treatment.

A method for the determination of surface contamination of various materials by 3H and 99Tc is reported. Both 3H and 99Tcm are widely used in chemical and clinical applications. The isotopes 99Tc, the decay product of 99Tcm, and 3H are soft beta-emitter radionuclides and the use of unsealed sources can frequently produce contamination and excessive internal dosing for workers. The removal of radionuclides from surfaces was effected with attapulgite, a clay with a high absorption capacity for many organic and inorganic substances. The determination was carried out by extracting the absorbed radionuclide from the clay and then measuring it in a beta-scintillation counter. The determination limits of the method, 20 Bq cm-2 for 3H and 100 Bq cm-2 for 99Tc, are below the "derived working limits" for these radionuclides.

Magnesium↗
PubMed1995

Determination of cadmium in whole blood and urine electrothermal atomic absorption spectrometry using palladium-based modifiers and in situ decontamination.

The determination of Cd in whole blood and urine by electrothermal atomic absorption spectrometry using Pd-based modifiers and in situ decontamination was studied. The performance of Pd, Pd + NH4NO3, and Pd + Mg(NO3)2 as modifiers were compared with respect to maximum pyrolysis and atomization temperatures, background attenuation, linear calibration range and matrix interference. Samples were diluted (1 + 4) with 0.1% Triton X-100 (blood) or 0.2% HNO3 (urine), and introduced onto the graphite tube platform already containing the in situ dried and decontaminated modifier. The influence of modifier volume and concentration, as well as that of the dilution ratio was investigated. The proposed procedure involves the use of Pd(NO3)2 + (Mg(NO3)2 as modifier, a pyrolysis temperature of 700 degree C and an in situ decontamination step of 1200 degrees C. The atomization temperature was 1700 degrees C. The detection limit (n = 10, k = 3) was 0.22 micrograms l-1 for both samples. Typical relative standard deviation values (n = 3) were below 3%. Using matrix-matched standards, good agreement was observed between experimental and reference values in the analysis of certified reference materials. Interlaboratory comparison data have confirmed the validity of the proposed analytical procedure.

Cadmium↗
PubMed2004

MgI2-catalyzed halo aldol reaction: a practical approach to (E)-beta-iodovinyl-beta'-hydroxyketones.

A novel generation of 1-iodo-3-siloxy-1,3-butadienes has been developed by reacting trimethylsilyl iodide (TMS-I) with alpha, beta-unsaturated ketones in dichloromethane at 0 degrees C without the use of any catalyst. The halo aldol reaction of these butadiene intermediates with aldehydes was efficiently carried out by using magnesium iodide as the catalyst. Twelve beta-iodo-alpha,beta-unsaturated-beta'-hydroxyketones (halo aldols) have been synthesized under the new condition with excellent geometric selectivity and good chemical yields (>80% chemical yields for 11 examples).

Catalysis↗
PubMed1998

Effect of potassium-magnesium citrate on upper gastrointestinal mucosa.

BACKGROUND: Potassium supplements may cause mucosal damage of the gastrointestinal tract. AIM: To evaluate the effect of a new potassium supplement, potassium-magnesium citrate (K-Mag), on upper gastrointestinal mucosa and to compare it with an older potassium supplement, potassium citrate (Urocit-K). METHODS: A randomized and double-blind study was conducted utilizing 36 healthy adults. Subjects were randomized into three groups: K-Mag (70 mmol/day K, 35 mmol/day citrate and 17.6 mmol/day Mg); Urocit-K (70 mmol/day K and 23.4 mmol/day citrate), and placebo. All subjects took 5 tablets b.d. of the allocated drug and 2 mg t.d.s. of glycopyrrolate for 7 days. On day 8, stool was examined for occult blood, a symptom score was calculated and an oesophagogastroduo-denoscopy was performed. Mucosal lesions were scored at five anatomic sites. RESULTS: Demographic characteristics and symptom score were similar in the three groups (< 10% with more than mild symptoms). There were no significant differences in the endoscopic scores at any site examined nor in the total scores among the three groups. Erosion or ulcers were found in 18% of K-Mag, 23% of Urocit-K and 17% of the placebo group. CONCLUSION: Short-term use of K-Mag does not appear to induce lesions in the upper gastrointestinal mucosa and its oral tolerance is similar to Urocit-K or placebo.

Adult↗
PubMed2000

Impact of citrate therapy on the circadian rhythm of urinary magnesium ammonium phosphate saturation in normal individuals.

BACKGROUND: Alkaline citrate has been used widely in the prevention of stone formation. However, the risk of struvite stone during the alkalinizing therapy has not been adequately studied in terms of magnesium ammonium phosphate saturation. METHODS: The circadian rhythm of the urinary saturation of magnesium ammonium phosphate was estimated by using the differential Gibbs' free energy values of magnesium ammonium phosphate before and during 5 days of treatment with sodium-potassium citrate (1 g t.i.d., 1 g q.i.d. or 3 g t.i.d.) in five healthy male volunteers. RESULTS: The magnesium ammonium phosphate saturation varied during the day, peaking far below the solubility product between 08.00 and 10.30 h and between 13.00 and 18.00 h. The mean peak levels were increased by each treatment regimen in comparison with the control day. The mean increase on day 1 was significant between 10.30 and 23.00 h with the 3 g t.i.d. regimen, but the mean saturation still remained below the solubility product throughout the day. CONCLUSIONS: The urinary magnesium ammonium phosphate saturation appeared hard to exceed the solubility product with a high dose of alkaline citrate.

Adult↗
PubMed2003

Annual changes of the incidence and clinical characteristics of magnesium ammonium phosphate urinary stones.

BACKGROUND: Magnesium ammonium phosphate (MAP) urinary stones account for the majority of staghorn stones and frequently cause a non-functioning kidney. In the present study, we examined the annual changes of the number and clinical characteristics of MAP stones. METHODS: The annual incidence of MAP stones was investigated in 2619 patients with urinary stones in whom composition of the stone was analysed at Chiba University Hospital between 1964 and 1999. In addition, the annual number of patients with MAP stones was examined at Funabashi Clinic. In a total of 644 patients with MAP stones, age and sex of the patients, location and size of the MAP stones, urinary cultures and etiological factors were analysed. RESULTS: The number of MAP stones in the lower urinary tract was relatively constant. In contrast, MAP stones in the upper urinary tract had dramatically decreased since 1989, resulting in an increase in the rate of MAP stones in the lower urinary tract. Age distribution of the MAP stone patients ranged from 10 years to > 80 years, with the majority aged 30-60 years. The proportion of larger MAP stones in the upper urinary tract increased. There was no significant difference in prevalence of urine cultures. Among etiological factors for MAP stones, difficulty on urination tended to be common in recent years. CONCLUSION: The number of MAP stones, especially in upper urinary tract, has been decreasing during the last decade. At present, treatment of urinary tract obstruction seems important for the management of MAP stones in lower urinary tract.

Adolescent↗
PubMed2000

Bladder calculi in children who perform clean intermittent catheterization.

OBJECTIVE: To examine the role of clean intermittent catheterization (CIC) as a possible predisposing risk factor for bladder calculi, assessing risk factors in patients with and without bladder augmentation, and to evaluate management options for bladder calculi in these patients. PATIENTS AND METHODS: The records of 403 patients who were using a regimen of CIC between January 1981 and March 1998 were reviewed to identify those forming bladder calculi; stones were diagnosed in 28 patients. The patients were categorized as: group 1, patients with no bladder augmentation who catheterized urethrally (227, group 1a) or via a Mitrofanoff conduit (18, group 1b); group 2, patients with augmented bladders who catheterized urethrally (100, group 2a) or via a Mitrofanoff conduit (58, group 2b). The incidence of bladder calculi in each group was determined and compared statistically where applicable. The success of the treatment options for stone management was reviewed. RESULTS: Bladder calculi developed in 5% of patients in group 1a, 8% in group 2a, 11% in group 1b, and 10% in group 2b; the incidence of calculi was not significantly different among the groups. Of these patients, 18 (64%) were asymptomatic at the time of diagnosis and significant bacteriuria was found in 23 (88%). Difficulty in catheterizing either the Mitrofanoff conduit or the native urethra was reported in 14 (50%) of these patients. Calculi were more often solitary (71%) and typically composed of struvite or apatite. Calculi were managed by open cystolithotomy in 15 patients (54%) and endoscopically in 13 (46%). Stones recurred in nine patients (32%) after treatment, comprising four of six patients treated endoscopically with electrohydraulic lithotripsy and in five of 15 after open cystolithotomy. The mean interval to recurrence was 22.8 months. CONCLUSION: These results suggest that patients on a regimen of CIC are at risk of developing bladder calculi but the incidence of calculi is not influenced by bladder augmentation. The presence of a Mitrofanoff conduit was associated with a slightly increased incidence of calculus formation. Open cystolithotomy was associated with a lower stone recurrence rate but there were too few patients to draw definitive conclusions.

Adolescent↗
PubMed2000

Potassium-magnesium citrate versus potassium chloride in thiazide-induced hypokalemia.

BACKGROUND: The purpose of this study was to compare the value of potassium-magnesium citrate (KMgCit) with potassium chloride in overcoming thiazide-induced hypokalemia. METHODS: Sixty normal subjects first took hydrochlorothiazide (HCTZ; 50 mg/day). After three weeks of treatment (or earlier if hypokalemia developed), they were randomized to take KMgCit (42 mEq K, 21 mEq Mg, and 63 mEq citrate/day) or potassium chloride (42 mEq/day) for three weeks while continuing on HCTZ. RESULTS: KMgCit significantly increased the serum potassium concentration from 3.42 +/- 0.30 mEq/L on HCTZ alone to about 3.8 mEq/L (P < 0.001). Potassium chloride produced a similar increase in serum potassium concentration from 3.45 +/- 0.44 mEq/L to about 3.8 mEq/L (P < 0. 001). KMgCit significantly increased the serum magnesium concentration by 0.11 to 0.12 mEq/L (P < 0.01), whereas potassium chloride produced a marginal decline or no significant change. KMgCit was less effective than potassium chloride in correcting HCTZ-induced hypochloridemia and hyperbicarbonatemia. KMgCit, but not potassium chloride, significantly increased urinary pH (by about 0.6 unit), citrate (by about 260 mg/day), and urinary magnesium. CONCLUSIONS: KMgCit is equally effective as potassium chloride in correcting thiazide-induced hypokalemia. In addition, KMgCit, but not potassium chloride, produces a small but significant increase in serum magnesium concentration by delivering a magnesium load, and it confers alkalinizing and citraturic actions.

Adult↗
PubMed2000

Dose-related cardiac electrophysiological effects of intravenous magnesium. A double-blind placebo-controlled dose-response study in patients with paroxysmal supraventricular tachycardia.

AIMS: The role of magnesium as an antiarrhythmic drug is yet not conclusive. Therefore, we performed a double-blind, randomized, placebo-controlled dose-response study of cardiac electrophysiological effects of intravenous magnesium. METHODS AND RESULTS: Thirty-six patients undergoing an electrophysiological evaluation for paroxysmal supraventricular tachycardia were randomized to one of the following dosages of intravenous magnesium (0, 5, 10 or 20 mmol). Conventional electrophysiological variables for sinus node function, atrial, atrioventricular node and ventricular conduction and refractoriness were measured before and after magnesium administration. Prolongation of the atrial-His interval was found at 5 mmol of magnesium compared with placebo and no further prolongation was observed at higher doses (-3 +/- 8, 11 +/- 9, 7 +/- 15, 11 +/- 16, for the dosages of 0, 5, 10 and 20 mmol of magnesium, respectively, P < 0.05). Measures of sinus node function, intra-atrial conduction and conduction through the Purkinje system were unaffected by magnesium. Male gender was associated with prolongation in atrial effective refractory period, in contrast to shortening in females: 2 +/- 43, 35 +/- 44, 36 +/- 33, 13 +/- 12 ms for males and 3 +/- 6, -12 +/- 11, -13 +/- 12, 0 +/- 23 ms for females, respectively (P < 0.001). CONCLUSION: Atrioventricular node conduction was prolonged by 5 mmol intravenous magnesium and no further prolongation was observed at higher dosages. At dosages of 5 and 10 mmol magnesium the atrial effective refractoriness was prolonged in males and shortened in females.

Adolescent↗
PubMed2001

An investigation into the effects of storage on the diagnosis of crystalluria in cats.

Urinalysis was performed on 41 cats with no history of urinary tract disease. Samples were divided into aliquots, stored under differing condition and then examined for the presence of crystalluria. Crystalluria was detected in at least one stored sample in 92% of cats fed a mixed wet/dry food diet compared to 24% in the fresh sample. Crystalluria was not detected in any sample or aliquot from cats fed all wet food diets.

Animal Feed↗