Crystallization in Gel Matrices: A New Experimental Model of Calcium Stone Formation1

Achilles, W.

doi:10.1159/000414488

Cited by 15 publications

(8 citation statements)

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“…For citric acid, trisodium citrate, isocitric acid and PP~ the inhibition was proportional to the concentration of inhibitor present in the reaction medium (from 0.25 to 3 mM); this is in agreement with previous studies demonstrating at pH 6, in seeded crystal growth systems with lower supersaturation, 50% inhibition at a citrate concentration of 0.1 or 0.4 mM [ 16,18,22]. For isocitric acid, Achilles [1] demonstrated in gel matrices an inhibition varying from 4% to 17% for 0.1-1 mM concentrations.…”

Section: Effects Of Various Compoundssupporting

confidence: 91%

“…Previous investigations used seeded crystal growth systems [18,21,22] or gel matrices [1] to study inhibitors of CaOx crystallization kinetics. It is difficult to compare crystal formation of CaOx in the present model with results reported in the literature because previous workers took into account only the growth of CaOx.…”

Section: Formation Of Calcium Oxalate Crystalsmentioning

confidence: 99%

“…1) is essentially related to crystal growth although nucleation continues even after ti. The slope of the turbidity curve was directly related to the kinetics of the reaction and was reduced in the presence of known inhibitors of CaOx formation [1,18,21,22].…”

Section: Formation Of Calcium Oxalate Crystalsmentioning

confidence: 99%

“…Moreover, most authors worked at different pH values; however, CaOx crystallization and in particular the effect of inhibitors must be evaluated in relation to pH [1,23,26,27]:…”

Section: Formation Of Calcium Oxalate Crystalsmentioning

confidence: 99%

“…The effect of inhibitors of CaOx crystallization has received particular attention because in vitro experiments can be done to investigate the contribution of various inhibitors to the total inhibitory activity of urine [8,11,25,28]. Several methods have been used to study inhibitors of CaOx crystal growth, but many are either time consuming or require expensive or specialized equipment [1,13,16,18,21,22,29].The present study reports a quick, easy and reproducible method for quantitating the inhibition of CaOx crystal growth by various compounds of low molecular weight, i.e. di-and tricarbocylic acids and pyrophosphate.…”

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A new approach to studying inhibitors of calcium oxalate crystal growth

et al. 1993

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The nucleation and crystal growth of calcium oxalate (CaOx) were studied at pH 5.5 using turbidimetric measurements at 620 nm of suspensions produced by mixing calcium chloride and sodium oxalate (initial conditions: Ca, 3 x 10(-3) M; Ox, 0.5 x 10(-3) M). CaOx crystallization kinetics were defined first by the induction time ti and then by the slope of turbidity as a function of time during the interval corresponding to a correlation coefficient r2 > 0.99. The technique described requires only a small amount of material, is quick, convenient, and can be used to study inhibitors of CaOx crystallization by comparing ti and the rate of crystal growth in the presence and absence of inhibitors. The effects on CaOx crystal growth of several low molecular weight compounds, i.e. di- and tricarboxylic acids, were examined. The majority of these compounds were inhibitors of crystal growth, the greatest effect being seen with citric acid (50% inhibition in the presence of 1.5 x 10(-3) M citric acid), isocitric acid (50% inhibition in the presence of 0.75 x 10(-3) M isocitric acid) and pyrophosphate (30% inhibition in presence of 0.15 x 10(-3) M pyrophosphate). The inhibitors' behaviour regarding the medium was studied without any assumptions about their possible mechanisms of action. Measurements of ionized calcium before and after the reaction, as well as the observation of crystals by scanning electron microscopy, allowed us to formulate the hypothesis that the effect of citric acid and tartaric acid can be attributed mainly to ion pairing, in contrast to that of pyrophosphate and the other carboxylic acids.

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Section: Effects Of Various Compoundssupporting

confidence: 91%

Section: Formation Of Calcium Oxalate Crystalsmentioning

confidence: 99%

Section: Formation Of Calcium Oxalate Crystalsmentioning

confidence: 99%

“…Moreover, most authors worked at different pH values; however, CaOx crystallization and in particular the effect of inhibitors must be evaluated in relation to pH [1,23,26,27]:…”

Section: Formation Of Calcium Oxalate Crystalsmentioning

confidence: 99%

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A new approach to studying inhibitors of calcium oxalate crystal growth

et al. 1993

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Die biologische und medizinische Bedeutung von Calciumphosphaten

2002

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Die anorganische Komponente der Hartgewebe (Knochen und Zähne) von Säugetieren besteht aus Calciumphosphat, hauptsächlich aus Hydroxylapatit. Auch die meisten pathologischen Verkalkungen, die zu oft schweren Erkrankungen führen, beruhen letztlich auf der Kristallisation von Calciumphosphaten an unerwünschten Orten im Körper. Medizinisch wichtig ist hier vor allem die Arteriosklerose, d. h. die Blockierung von Blutgefäßen durch Cholesterin und Calciumphosphate. Die Kariesbildung beruht auf dem Ersatz des wenig löslichen, harten Hydroxylapatits durch andere, besser lösliche und weichere Calciumphosphatphasen. Osteoporose ist eine Demineralisierung von Knochen. Chemisch kann man die Bildung von Knochen und Zähnen genau wie die pathologische Verkalkung (Arteriosklerose) als eine In‐vivo‐Kristallisation bezeichnen, ebenso wie man Karies und Osteoporose als In‐vivo‐Auflösung von Calciumphosphat beschreiben kann. Calciumphosphate sind an vielen Stellen im Körper präsent. Viele Biomaterialien mit hoher Biokompatibilität beruhen daher auf diesen Materialien. Calciumphosphatzemente werden als Knochenersatz verwendet, und Titan‐Implantate zum Zahn‐ oder Hüftgelenkersatz werden mit Calciumphosphaten beschichtet, um das Anwachsen von Knochen und damit die mechanische Stabilität zu erhöhen. In diesem Aufsatz wird die biologische und medizinische Bedeutung der Calciumphosphate aus dem Blickwinkel eines Chemikers beleuchtet und an Beispielen erläutert.

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Biological and Medical Significance of Calcium Phosphates

Dorozhkin¹,

Epple²

2002

Angew. Chem. Int. Ed.

1,840

1,252

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The inorganic part of hard tissues (bones and teeth) of mammals consists of calcium phosphate, mainly of apatitic structure. Similarly, most undesired calcifications (i.e. those appearing as a result of various diseases) of mammals also contain calcium phosphate. For example, atherosclerosis results in blood-vessel blockage caused by a solid composite of cholesterol with calcium phosphate. Dental caries result in a replacement of less soluble and hard apatite by more soluble and softer calcium hydrogenphosphates. Osteoporosis is a demineralization of bone. Therefore, from a chemical point of view, processes of normal (bone and teeth formation and growth) and pathological (atherosclerosis and dental calculus) calcifications are just an in vivo crystallization of calcium phosphate. Similarly, dental caries and osteoporosis can be considered to be in vivo dissolution of calcium phosphates. On the other hand, because of the chemical similarity with biological calcified tissues, all calcium phosphates are remarkably biocompatible. This property is widely used in medicine for biomaterials that are either entirely made of or coated with calcium phosphate. For example, self-setting bone cements made of calcium phosphates are helpful in bone repair and titanium substitutes covered with a surface layer of calcium phosphates are used for hip-joint endoprostheses and tooth substitutes, to facilitate the growth of bone and thereby raise the mechanical stability. Calcium phosphates have a great biological and medical significance and in this review we give an overview of the current knowledge in this subject.

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Crystallization in Gel Matrices: A New Experimental Model of Calcium Stone Formation1

Cited by 15 publications

References 0 publications

A new approach to studying inhibitors of calcium oxalate crystal growth

A new approach to studying inhibitors of calcium oxalate crystal growth

Die biologische und medizinische Bedeutung von Calciumphosphaten

Biological and Medical Significance of Calcium Phosphates

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