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 541 records · Page 30Linked to original sources

Chemolysis of urinary calculi.

Irrigant chemolysis was developed to collaborate with open surgery, removing the residual fragments. With the worldwide diffusion of the procedures performed by the endourologist in the early 1980s and the present availability of ESWL, however, direct irrigation of stones has a reduced field of influence even as an adjunctive measure. Urologists have applied economic analysis to their clinical practices, and the findings related to irrigant chemolysis made this technique an unusual procedure. The cost to the providers of medical care, the burden on the patient in terms of suffering and loss of productivity, and the amount of time required to liberate the patient even partially from the stones make irrigant chemolysis an inauspicious scenario. In this era of cost containment and decreasing length of stay, it is increasingly difficult to justify hospital admissions for this form of therapy. Being simultaneously more expensive and less effective than the existing alternatives, local chemolysis should be discarded, except for special situations, such as patients at high risk for any surgical procedure. Oral chemolysis preserves reduced indications, for example as an adjuvant to an endourologic operation or ESWL in special situations. As long as urinary stones continue to afflict humans, chemolysis is likely to retain a limited but important role in their management.

Calcium Oxalate↗

Treatment options in struvite stones.

Urinary calculi have plagued man over the centuries. The epidemiology and pathogenesis of infection have been studied. The curative treatment remains problematic. Without therapy, a vicious cycle of stone formation occurs. This results in renal damage and even death. Multimodality therapy is the key. Nonoperative treatment leads to progressive renal damage. The combination of maximal surgical ablation and medical therapy is synergistic. The combination of PCNL-ESWL has not appeared to produce ill effects. PCNL-ESWL is a less morbid surgical alternative than open surgical procedures. Adjunctive medical therapy, such as culture-specific antibiotics and urease inhibitors, complements surgical ablation by reducing the morbidity with persistent UTIs and stone recurrence. The urologist today must approach struvite staghorns with a vast armamentarium of surgical and medical techniques. Each patient requires a unique solution.

Humans↗

Silicic acid (Si(OH)(4)) is a significant influence upon the atomic absorption signal of aluminium measured by graphite furnace atomic absorption spectrometry (GFAAS).

We have identified silicic acid (Si(OH)(4)) as an important modifier of the absorbance signal of aluminium measured by graphite furnace atomic absorption spectrometry (GFAAS). The presence of Si(OH)(4) enhanced the signal by as much as 50%. The extent of the enhancement was dependent upon both [Al] and [Si(OH)(4)] and was maximal when [Al]< or =4.44 micromol dm(-3) and [Si(OH)(4)]> or =0.50 mmol dm(-3). The enhancement of the Al absorbance signal was not linearly related to [Si(OH)(4)] and the effect was, generally, saturated, for all [Al] tested, at [Si(OH)(4)]> or =0.50 mmol dm(-3). Si(OH)(4) was significantly more effective in enhancing the Al absorbance signal than Mg(NO(3))(2). However, the co-occurrence of 10 mmol dm(-3) Mg(NO(3))(2) and 2 mmol dm(-3) Si(OH)(4) in samples abolished the enhancement due to Si(OH)(4). The presence of Si(OH)(4) in samples could result in an overestimation of the Al content of those samples by as much as 50%. Errors in the measurement of Al in samples containing Si(OH)(4) could be prevented using matrix-matched calibration standards. Our observation could have serious implications for the determination of Al in aqueous samples of both geochemical and biological interest. It may also point towards the application of Si(OH)(4) as a novel and effective matrix modifier in the determination of Al by GFAAS since the inclusion of Si(OH)(4) in standards and samples improved the limit of detection of Al from ca 8 nmol dm(-3) to 3 nmol dm(-3).

Absorption↗

Inhibition of myosin ATPase by metal fluoride complexes.

Magnesium (Mg2+) is the physiological divalent cation stabilizing nucleotide or nucleotide analog in the active site of myosin subfragment 1 (S1). In the presence of fluoride, Mg2+ and MgADP form a complex that traps the active site of S1 and inhibits myosin ATPase. The ATPase inactivation rate of the magnesium trapped S1 is comparable but smaller than the other known gamma-phosphate analogs at 1.2 M-1 s-1 with 1 mM MgCl2. The observed molar ratio of Mg/S1 in this complex of 1.58 suggests that magnesium occupies the gamma-phosphate position in the ATP binding site of S1 (S1-MgADP-MgFx). The stability of S1-MgADP-MgFx at 4 degrees C was studied by EDTA chase experiments but decomposition was not observed. However, removal of excess fluoride causes full recovery of the K+-EDTA ATPase activity indicating that free fluoride is necessary for maintaining a stable trap and suggesting that the magnesium fluoride complex is bonded to the bridging oxygen of beta-phosphate more loosely than the other known phosphate analogs. The structure of S1 in S1-MgADP-MgFx was studied with near ultraviolet circular dichroism, total tryptophan fluorescence, and tryptophan residue 510 quenching measurements. These data suggest that S1-MgADP-MgFx resembles the M**.ADP.Pi steady-state intermediate of myosin ATPase. Gallium fluoride was found to compete with MgFx for the gamma-phosphate site in S1-MgADP-MgFx. The ionic radius and coordination geometry of magnesium, gallium and other known gamma-phosphate analogs were compared and identified as important in determining which myosin ATPase intermediate the analog mimics.

Acrylamide↗

Optimization of a cultural medium for bacteriocin production by Lactococcus lactis using response surface methodology.

The medium composition for bacteriocin production by Lactococcus lactis ATCC 11454 was optimized using response surface methodology. The selected six factors based on CM medium were sucrose, soybean peptone, yeast extract, KH(2)PO(4), NaCl, and MgSO(4).7H(2)O. Fractional factorial designs (FFD) and the path of steepest ascent were effective in searching for the main factors and approaching the optimum region of the response. By a 2(6-2) FFD, sucrose, soybean peptone, yeast extract, KH(2)PO(4) were found to be significant factors and had positive effects on cell growth, however, only soybean peptone and KH(2)PO(4) were shown to be the two significant factors for bacteriocin production and had negative and positive effects, respectively. The effects of the two main factors on bacteriocin production were further investigated by a central composite design and the optimum composition was found to be 1% sucrose, 0.45% soybean peptone, 1% yeast extract, 2.84% KH(2)PO(4), 0.2% NaCl, and 0.02% MgSO(4) x 7H(2)O. The optimal medium allowed bacteriocin yield to be doubled compared to CM medium.

Bacteriocins↗

Medical management of male and female cats with nonobstructive lower urinary tract disease.

This case is typical of recurrent urolithiasis managed by repeated surgery. Retrospective assessment of the disorder indicates the need for quantitative analyses of uroliths removed by cystotomy. Compliance of the owners with recommendations to minimize recurrent urolithiasis might have been beneficial. Results of medical therapy designed to induce dissolution of uroliths in this case are representative of preliminary findings of medical dissolution of naturally occurring struvite uroliths in ten other cats. It is of interest that the uroliths dissolved even though no effort was made to induce diuresis. The underlying cause of UTI in this patient may have been damage to the lower urinary tract induced by previous diagnostic and therapeutic procedures and/or sterile struvite uroliths that compromised local host defense mechanisms. Lack of urease production by the uropathogens suggests that they did not play a causative role in formation of uroliths. The need for preventative therapy of recurrent formation of uroliths after their medical dissolution is worthy of further comment. In this patient, specific measures to prevent urolith recurrence were not initiated because it is a part of a prospective clinical study. In the event uroliths recur, medical therapy designed to induce dissolution of uroliths would be repeated. Need for long-term preventative therapy would be dependent on the time interval between recurrent episodes (weeks, months, or years), and the effectiveness of medical therapy for urolith dissolution. Long-term prophylactic therapy would include urine acidifiers and diets low in magnesium.

Ammonium Chloride↗

Treatment and prevention of feline struvite urolithiasis.

A diet providing less than 20 mg of magnesium per 100 kcal that maintains urine pH near 6.0 3 to 5 hours after eating, or a diet providing this amount fo magnesium (see Table 2) with 1 gm of ammonium chloride or 1.5 gm of dl-methionine added daily, should be fed for 1 to 3 months to dissolve struvite uroliths (see Fig. 1). The low-magnesium diet should be fed indefinitely to prevent recurrence, because struvite urolithiasis and all of its effects (hematuria, pollakiuria, and/or complete to partial obstruction to urinary excretion) recurs repeatedly in cats that have previously experienced the condition if they are returned to regular cat food. In contrast, if a diet low in magnesium is fed, recurrence is uncommon. For cats that have never been affected, feeding a low-magnesium ration is unnecessary. For all cats, the following measures are recommended: encourage exercise, allow frequent urination, prevent obesity, decrease confinement, keep the litter box clean, and always have palatable water readily available.

Animal Feed↗

Crystalluria. Observations, interpretations, and misinterpretations.

Crystalluria results from oversaturation of urine with crystallogenic substance. However, oversaturation may occur as a result of in vitro as well as in vivo events. The microscopic appearance of crystals only represents a tentative identification of their composition because variable conditions associated with their formation, growth, and dissolution may alter their appearance. Definitive identification is dependent on physical methods such as optical crystallography, x-ray diffraction, and electron microscopic analysis.

Animals↗

Etiopathogenesis of canine struvite urolithiasis.

Urine must be oversaturated with magnesium ammonium phosphate for struvite uroliths to form. Oversaturation of urine with magnesium ammonium phosphate may be associated with several factors, including urinary tract infections with urease-producing microbes, alkaline urine, diet, and genetic predisposition. Of the urease-producing microbes, staphylococci are most struvitogenic in dogs. The precise mechanisms resulting in formation of sterile struvite uroliths in dogs have not been determined.

Animals↗

Canine distal renal tubular acidosis and urolithiasis.

Distal RTA is characterized by decreased distal renal tubular hydrogen ion secretion, decreased ability to acidify urine, hypercalciuria, hyperphosphaturia, hypocitraturia, and metabolic acidosis. Because of the resulting alterations in urine composition and pH, patients with distal RTA are predisposed to urolithiasis and renal calcification. Diagnosis of distal RTA is important because it is a potentially reversible disorder that, left untreated, may cause nephrocalcinosis, recurrent urolith formation, moderate to severe metabolic acidosis, and renal failure.

Acidosis, Renal Tubular↗

Methods of analysis of canine uroliths.

Accurate analysis of urinary calculi is essential for greater understanding of urinary stone disease and initiation of effective management and preventive measures. Quantitative and qualitative analysis of uroliths are discussed in this article.

Animals↗

Comparison of qualitative and quantitative analyses of canine uroliths.

A study was performed to compare qualitative test results of canine uroliths with quantitative test results. Qualitative test results were in agreement with quantitative test results in only 96 of 223 specimens (43 per cent). Lack of agreement was caused by false-negative qualitative test results (85 of 223), false-positive qualitative test results (15 of 233), and a combination of false-negative and false-positive qualitative test results (27 of 233). This study indicates that the veterinary profession should abandon exclusive use of qualitative chemical test kits for uroliths.

Animals↗

Medical dissolution of canine struvite uroliths.

Medical therapy is an effective method of canine struvite urolith dissolution. Recommendations include (1) eradication or control of urinary tract infection (if present), (2) use of calculolytic diets, and (3) administration of urease inhibitors to patients with persistent urinary tract infection caused by urease-producing microbes.

Animals↗

Feline crystalluria. Detection and interpretation.

Crystalluria results from oversaturation of urine with crystallogenic substances. However, oversaturation may occur as a result of in vivo and in vitro events. Therefore, care must be used not to overinterpret the significance of crystalluria. Evaluation of urine crystals may aid in (1) detection of disorders predisposing cats to urolith or matrix-crystalline urethral plug formation; (2) estimation of the mineral composition of uroliths or urethral plugs; and (3) evaluation of the effectiveness of medical protocols initiated to dissolve or prevent urolithiasis.

Animals↗

Analysis of 77,000 canine uroliths. Perspectives from the Minnesota Urolith Center.

Of the hundreds of minerals that are found in the earth, most canine uroliths are comprised of only six types: (1) magnesium ammonium phosphate, (2) calcium oxalate, (3) calcium phosphates, (4) ammonium urate and other salts or uric acid, (5) cystine, or (6) silica. Each type has characteristics that allow its identification. During the past two decades, the prevalence of calcium oxalate canine uroliths has dramatically increased, while struvite has decreased. The most effective treatment and prevention protocols are based on knowledge of the primary mineral type comprising the urolith.

Age Distribution↗