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PubMed1988

Effects of magnesium on calcium phosphate formation.

All biological calcium phosphates form in various neutral aqueous solutions containing [CaCl2] = 1 or 3 mM, [MgCl2] = 0-9 mM, [Na2HPO4] = 0.1-90 mM and NaCl (total 300 mosM) kept quiescently at 37 degrees C for 21 days. In all solutions containing 1 mM Ca and in solutions with [Ca] = 3 mM and [PO4] less than 10 mM, heterogeneous nucleation of octa-calcium phosphate (for Mg/Ca less than or equal to 1) or brushite (for Mg/Ca greater than 1) was observed; the former transforming to apatite with time. In contrast, homogeneous nucleation of an unstable amorphous calcium magnesium phosphate occurred in solutions with [Ca] = 3 mM and [PO4] greater than or equal to 10 mM, transforming to apatite, to brushite, and to whitlockite (and newberyite) depending on Mg/Ca and [PO4] values.

Apatites↗
PubMed1988

[Comparative study, with photoelectron spectroscopy of the adsorption of phospholipids by 3 fibrous silicate minerals (chrysotile, crocidolite, attapulgite)].

The method used in this study for preparing mineral samples has allowed us to obtain a highly reproducible surface state, which in turn means that we can better exploit the results of the XPS analysis. With high initial concentrations, the three minerals studied appeared to be covered with a bilayer of phospholipids. The greatest adsorption was obtained with initial phospholipid concentrations of 100, 150 and 300 micrograms/ml for crocidolite, chrysotile and attapulgite respectively. It would appear that these differences in surface reactivity can be related to the different levels of risk associated with the inhalation of these fibres.

1,2-Dipalmitoylphosphatidylcholine↗
PubMedDate not supplied

[The effect of pyrophosphate on the rigor fibers of rabbit m. psoas fibers].

The effect of MgPPi on the rigor force of glycerinated fibres in the range of ionic strength 75-250 mM at two temperatures 18 degrees and 5 degrees C was studied. At 18 degrees C the maximum of this effect was above the range of average ionic strength. At 5 degrees C the greatest effect of MgPPi was observed at low ionic strength.

Animals↗
PubMed1988

[Need for the differentiation of apatite and carbonate apatite].

With extensive analytical and clinical examinations it is shown that the proof of carbonate in apatite may allow no additional reference of an infection with urea-splitting bacteria. With certain analytical methods the presence of carbonate is demonstrable in each urinary calculus apatite phase. Carbonate-bearing apatite indeed is accompanied frequently with struvite, but may be occur also without an infection. Therefore, in the future it should be renounced on the differentiation of apatite and carbonate apatite in routine analyses of urinary calculi.

Apatites↗
PubMed1986

[Studies on urolithiasis. The histochemistry of the kidney tissues and stones from patients with urolithiasis].

In this study, 17 kidney tissue specimens and 29 renal stones were obtained from patients with urolithiasis. Control kidney specimens were dissected from 7 individuals not suffering from urolithiasis. The tissue specimens were fixed with 1% cetylpiridinium chloride (CPC) in 10% formalin (for 24 hours at room temperature). Then the kidney tissue specimens were embedded in paraffin and stained with hematoxylin-eosin for general observation as well as histochemically for demonstration of complex carbohydrates. Also, stone specimens were embedded in epon and thin sections made by the mineral polishing specimen preparation, and stained along with the kidney tissues. For identifying individual acidic and neutral carbohydrates, the enzyme digestion was performed for some tissue sections prior to histochemical staining. The stone-forming kidney tissues, normal kidney tissues and urinary stones (calcium oxalate, mixed, struvite) contained some glycosaminoglycans and neutral glycoproteins, but uric acid stones and cystine stones did not. The results of digestion with enzymes indicated that calcium oxalate stone-forming kidney tissue contains heparitin (heparan) sulfate; mixed stone-forming tissue contains sialic acid, hyaluronic acid, chondroitin sulfate A, B, C and heparitin (heparan) sulfate; struvite stone-forming tissue contains sialic acid, hyaluronic acid, chondroitin sulfate A, C and heparitin (heparan) sulfate; and cystine stone-forming tissue contains sialic acid, chondroitin sulfate A, C and heparitin (heparan) sulfate. The stone organic matrix is classified into the amorphous and stratiform types. The amorphous type matrix contains chondroitin sulfate A, B, C and heparitin (heparan) sulfate, and the stratiform type matrix also contains sialic acid and hyaluronic acid. The stone-forming kidney tissues, normal kidney tissues and stones (calcium oxalate, mixed, struvite) contain an appreciable amount of alpha-D-glucose, alpha-D-mannose and beta-D-galactose, but the uric acid stones and cystine stones do not contain sugar residues. Since the specific glycosaminoglycan composition differed for kidneys of different mineral content and stones of different morphological type, we believe that some glycosaminoglycans in kidneys and amorphous type matrix might play the role of a nucleating agent, and that a stratiform type matrix encourages stone enlargement.

Adult↗
PubMed1985

X-ray microanalysis of urinary stones, a comparison with other methods.

A previous study of urinary stones by a combined electron microscopy demonstrated the potential of scanning electron microscopy and X-ray analysis as an analytic tool for urinary stones. Electron diffraction was chosen for the final confirmation of crystals in the study. Although electron diffraction is highly accurate for this purpose, it is desirable to establish the sensitivity of X-ray analysis for the identification of stone components relative to the more commonly used methods. Eighty six consecutive urinary stones were analyzed by X-ray analysis and the findings were compared with those of X-ray diffraction, infrared spectrometry and chemical analysis. The results indicate that X-ray analysis exceeds X-ray diffraction and infrared spectroscopy in its sensitivity for the identification of stone components several fold. This was largely due to the inability of the latter methods to detect apatite in more than half of the apatite containing stones. The findings in X-ray analysis had the best correlation with chemical analysis, which was applied mainly to the detection of apatite. X-ray analysis is particularly suited for the detection of rare and minor inorganic components of urinary stones such as silica and gypsum, and is obviously one of the most powerful tools for the analysis of urinary stones. Further application of X-ray analysis to urinary stone is likely to discern rare inorganic components of urinary stones overlooked by other methods.

Calcium Oxalate↗
PubMed1987

Proximity and ligand-induced movement of interdomain residues in myosin subfragment 1 containing trapped MgADP and MgPPi probed by multifunctional cross-linking.

The conformations of myosin subfragment 1 containing trapped MgADP or MgPPi have been studied by investigating the spatial disposition of the remainder of the subfragment 1 structure to the covalently bridged ATPase-related thiols SH1 and SH2. This has been done by synthesizing a trifunctional photoactivatable reagent 4,4'-bis(N-maleimido)benzophenone and reacting it with subfragment 1 in the presence of these ligands. Modification of subfragment 1 by this reagent mimics closely the changes in the ATPase properties as noted previously for modification with p-phenylenedimaleimide. In addition, noncovalent trapping of nucleotide also results, presumably by the bridging of the SH1 and SH2 thiols. On photolysis, cross-linking from the reagent bridging the thiols to other regions in subfragment 1 can be observed, but the extent and course of the photoinduced cross-linking depend on the nature of the trapped ligand. For subfragment 1 with trapped MgADP, a high efficiency cross-linking occurs between the 21-kDa segment and the 50-kDa segment. With MgPPi as the trapped ligand, low efficiency cross-linking occurs between the bridged thiols and either the 27-kDa N-terminal or the 50-kDa segments of the heavy chain. These results indicate that without the adenosine moiety, the binding of MgPPi to subfragment 1 leaves the protein in a flexible state so that residues in both the 27-kDa and the 50-kDa segment can move within the cross-linking span of the activated benzophenone triplet. The trapping of MgADP apparently results in a more rigid state for the subfragment 1 in which residues in the 50-kDa segment are spatially close to the bridged thiols, thus enabling photocross-linking to proceed with higher efficiency.

Adenosine Diphosphate↗
PubMed1988

[Factors influencing fluorine absorption and excretion in people and animals].

Factors that make fluorine absorption and excretion easy or difficult from organisms of people and animals have been analysed. Fluorine is easily absorbed in presence of alimentary fat from soluble dust, from water environment, especially from an acid one. Compounds of calcium, magnesium, aluminium, microelements and various high protein diet make fluorine absorption difficult. Compounds that easily absorb fluorine, namely compounds of calcium, magnesium, aluminium, boron, phosphorus and vitamin C as well as climatic conditions (increasing perspiration) make fluorine excretion from organisms easy. Fluorine excretion is made difficult in the period of intensified mineralization and lactation processes. The age of the person is also important.

Absorption↗
PubMed1987

Attapulgite.

Explore the source record for details and available documents.

Animals↗
PubMed1988

Improved determination of selenium in serum by Zeeman atomic absorption spectrometry.

We have improved Zeeman atomic absorption spectrometric determination of selenium in serum by using an acidic solution of Ag + Cu + Mg as a matrix modifier and performing the charring step in flowing O2. Under these conditions, we could calibrate serum results with selenium standards in bovine albumin solutions. Mean analytical recovery was 98%, and the CV was 1.8% within runs, 2.9% between runs. Analysis of Reference Materials from the U.S. National Bureau of Standards (SRM 909 and RM 8419) yielded the values of 106 (SD 2.4) and 15 (SD 1.6) microgram/L, respectively, in good agreement with the expected values (106 and 16, respectively). The method--being reliable and relatively simple and rapid--is suitable for use in epidemiological screenings. Mean selenium concentrations in serum sampled from 274 adults in central Italy were 90 (SD 15) microgram/L. For 11-year-old children, these values were lower and showed a tendency to sex-related difference: 82 (SD 9.9) microgram/L for 97 boys, 78 (SD 9.3) microgram/L for 90 girls.

Adult↗