engleski

Light Microscopy: Model and Real Systems

Various mineral cations (Ca^2+, Mg^2+, Na^+, Zn^2+) and anions (phosphate, oxalate, urate ions) can form biominerals which constitute normal (bone, teeth, shells) and pathological mineralized tissues (stones, caries, gouty arthritis, arteriosclerosis) in human body, plants and animals. The formation of biominerals, interpreted in a simple way, is the formation of sparingly soluble salts from body fluids (blood, serum, urine) within an organic macromolecular matrix. Processes involved in pathological mineralization are of special interest due to the great medical and social problems that they cause. In this work, the formation of compounds, frequently found in urinary calculi, calcium oxalate monohydrate (COM) and/or calcium oxalate dihydrate (COD), phosphate (e.g. calcium hydrogen phosphate dihydrate (DCPD)), uric acid (H_2U) and magnesium ammonium phosphate hexahydrate – struvite (S) and/or magnesium hydrogen phosphate trihydrate – newberyite (N), was studied in the model systems at physiological conditions (pH, ionic strength, initial reactant concentrations, temperature). The precipitates obtained were characterized by FT-IR spectroscopy, X-ray diffractometry and light microscopy. Their composition and morphology were compared with the crystals formed in urine. Figure 1 compares typical morphologies of calcium oxalate (a and a1), calcium phosphate (b and b1), uric acid (c and c1) and struvite (d and d1) formed in model systems (a-d) and in urine, (a1-d1). The investigations demonstrated that the composition and morphology of the crystals formed in all model systems were extremely sensitive to the precipitation conditions (composition and temperature of the mother liquid, the way of mixing the reactants, pH, ionic strength etc.). The presence of variety of crystal composition and habit in human urine (crystalluria) was compared with the urine biochemical parameters and composition of calculi. It is not possible to identify the stone-formers on the basis of crystalluria only. Reference: 1. A. Hesse, D. Heimbach ; World J Urol 17: 308-315, 1999

light microscopy; biominerals; urinary calculi; model system; real system

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