Composition of apatites in human urinary calculi

Estudio de un cálculo intestinal en un paciente con adenocarcinoma de colón. ¿es similar a los cálculos renales?

This work shows the study performance to intestinal enterolithis from a 91 year old patient with multiple enterolithiasis confirmed by abdominal X-ray and TAC analyses showing the presence of intestinal, renal and bile stones. This enterolithis is associated with colon adenocarcinoma. The enteroliths were obtained by hemicolectomia and were analyzed by infrared spectroscopy (IR), giving non-stoichiometry carbonate apatite whitloquite-like with, possibly, organic material. By atomic emission spectroscopy we found Ca, Mg, K, Na and K (mg/100 mg of calculi) and Zn, Ba, Mn, Fe, Cu, Si, Ti and Br in minor proportion (microg/100 mg of calculi). Because of calculi morphology and the IR spectra (non-stoichiometry carbonate apatite) we carried out analysis by high performance liquid chromatography (HPLC) and found coproporphyrin (about microg/g of calculi) and uroporphyrin, protoporphyrin and heptacarboxy-porphyrin in minor extent. Calculi were also studied by scanning electronic microscopy and EDX and X-ray diffraction giving crystals of CaP4O11. All these results show that intestinal enteroliths composition are similar to renal calculi although its morphology differs from renal calculi.

Spectroscopic and ultrastructural comparative study of cystine calculi in humans and dogs

The careful analysis of cystine calculi may be important to detect the presence of other urinary alterations (such as hyperuricosuria, hypercalciuria, hyperoxaluria or bacterial infections) that coexist with cystinuria in many patients. For this reason, in the present study, 14 human and 17 canine cystine uroliths have been studied by infrared spectroscopy (IR), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). According to the infrared analysis, most of the human and canine stones were composed of nearly pure cystine. However, in these calculi of apparently pure cystine, the study by SEM and EDX showed in many cases the presence of small amounts of calcium apatite. The infrared study of several samples heated at 750 degrees C confirmed the presence of phosphate, when it was difficult to detect this component in the spectra of the original samples owing to band overlapping. Other components detected in varying proportions in cystine calculi were magnesium ammonium phosphate hexahydrate (struvite), calcium hydrogen phosphate dihydrate (brushite), calcium oxalate (mono and/or dihydrate) and, in one case, a drug (oxolinic acid).

Infrared and atomic spectrometry analysis of the mineral composition of a series of equine sabulous material samples and urinary calculi

Atomic spectrometry has been used in 20 samples of equine urinary sabulous deposits in order to detect minor elements accompanying the predominant element, calcium, which is present in the form of calcium carbonate (calcite and/or vaterite). The elements measured have been (besides calcium) magnesium, sodium, potassium, iron, copper and manganese. Phosphates, sulphates and silica are frequently present as minor constituents of equine urinary sabulous deposits and uroliths, but their detection can be difficult by infrared (IR) spectroscopy in the original samples due to overlapping with the bands of calcium carbonate. For that reason, the calcination residues of six urinary calculi and 33 samples of sabulous material have been studied by IR spectroscopy and energy dispersive X-ray (EDX) analysis. The results confirm the presence of the above mentioned minor constituents in most samples studied.

Rapid computer-assisted infrared analysis of urinary calculi using photoacoustic detection

The application of commercial spectrum-analysing software to quantitative analysis of urinary stones by Fourier transform infrared spectrophotometry is described. The infrared technique is straightforward in comparison with other stone analysis procedures of similar scope and affords significant time savings. The use of partial least squares regression in the analysis program enables better quantitation of stone components than has been hitherto possible using infrared methods. All the principal and many less common stone constituents can be detected and measured. Photoacoustic detection was employed, thus enabling non-destructive analysis with minimal sample preparation. A comparison is made between the infrared procedure and the hybrid thermogravimetric plus "wet" chemistry technique, which it has superseded for routine urinary stone analysis in the author's department.

Hydrogen bonds between protein side chains and phosphates and their role in biological calcification

Poly(L-histidine)-phosphate (H2PO4-, HPO4(2-)) and poly(L-glutamate)-phosphate systems (residue/phosphate, 1:1) in the presence of Ca2+ are studied by infrared spectroscopy. In the poly(L-histidine)-phosphate systems N...HOP in equilibrium NH+...O-P hydrogen bonds are formed where most phosphate protons are found at the histidine ring. With an increase in the degree of hydration the proportion of the proton limiting structure NH+...O-P increases. In the poly(L-glutamate)-dihydrogen phosphate system most phosphate protons are found at the carboxylate groups. Different behavior is observed for poly(L-glutamate)-hydrogen phosphate mixtures, where the residence time of the phosphate proton at the hydrogen acceptor carboxylate group is very short. This residence time increases, however, with increasing humidity. All these results support the triphasic theory of biological calcification involving a tripartite protein-calcium-phosphate complex where these hydrogen bonds can be present. The behavior of these hydrogen bonds can also explain the formation of a nidus of calcium phosphate salts in calcium oxalate-containing urinary calculi.

The composition of recrystallized bone mineral

Bone mineral and synthetic calcium-deficient carbonate apatite (CDCA), when defined in terms of their respective thermal stabilities and ignition products, are homologous. When heated to 550 degrees, they may have a structure similar to that of the mineral dahllite. When heated to temperatures greater than 550 degrees, CDCA (like bone mineral) losses its structural CO3 and is recrystallized to whitlockite and/or OH-apatite, depending on its stoichiometry.

Ultrastructural study of apatites in human urinary calculi

Using transmission and scanning electron microscopy, we have studied the ultrastructure of a number of urinary calculi, mainly composed of calcium phosphate. Three fundamental kinds of calcium phosphates were detected: nonstoichiometric carbonate apatite, nonhexagonal octacalcium phosphate, and calcium-magnesium whitlockite. The influence that the organic matter, substitutions in the phosphate lattice of CO3 and Mg, and apatitic stoichiometry have on the ultrastructure of the calcium phosphate calculi has been detailed. An originating apatitic unity named U2 is assumed to be the responsible for all the different structures of calcium apatites appearing in renal calculi. On the basis of our observations, a mechanism whereby apatites grow is postulated; magnesium functions as an inhibitor for the growing mechanism.

Is there a "citrate-apatite" in biological calcified systems?

An apatite containing citrate ions has been synthesized. Measurements of specific surface, as well as Ca/P ratio, infrared, X-ray, and calcination data are all consistent with the idea that citrate ion substitutes for PO4(3-) ion on the apatitic surface.