There are various organic and inorganic constituents in kidney stones. Among them, calcium oxalate monohydrate (COM) is the primary inorganic constituent of kidney stones. However, the mechanisms of formation of kidney stones are not well understood. In this regard, a basic study is carried out for better understanding of nucleation, crystal growth and/or aggregation of formed COM crystals. The primary nucleation of calcium oxalate monohydrate is studied at the laboratory scale using turbidity measurements. Calcium chloride and potassium oxalate solutions are mixed and then added to a Turbidimeter tube for continuous recording of turbidity. Induction time (time to induce formation of detectable crystals) is estimated from time-turbidity graphs. The effect of some urinary species, such as oxalate and calcium, on nucleation and crystallization characteristics of COM is determined by particle size distribution analysis, measuring weight of crystals and calculation of relative supersaturation. The classical nucleation theory is applied at high supersaturation ratios (SR) ranging from 1.6 to 2.2. The results indicate that nucleation rate increases with increasing supersaturation ratio from 0.81 x 10 28 nuclei/cm 3 .sec at 1.6 SR, to 18.02 x 10 28 nuclei/cm 3 .sec at 2.2 SR. On the other hand, free energy change and radius of critical nucleus are decreased as supersaturation ratio is increased. The nucleation rates are higher than those reported in literature. Such discrepancy is discussed on the bases of differences in experimental techniques.

Kidney stones consist of various organic and inorganic compounds. Calcium oxalate monohydrate (COM) is the main inorganic constituent of kidney stones. However, the mechanisms for the formation of calcium oxalate kidney stones are not well understood. In this regard, there are several hypotheses including nucleation, crystal growth and/or aggregation of formed COM crystals. The effect of some urinary species such as oxalate, calcium, citrate, and protein on nucleation and crystallization characteristics of COM is determined by measuring the weight of formed crystals and their size distributions under different chemical conditions, which simulate the urinary environment. Statistical experimental designs are used to determine the interaction effects among various factors. The data clearly show that oxalate and calcium promote nucleation and crystallization of COM. This is attributed to formation of a thermodynamically stable calcium oxalate monohydrate resulting from supersaturation. Citrate, however, inhibits nucleation and further crystal growth. These results are explained on the basis of the high affinity of citrate to combine with calcium to form soluble calcium citrate complexes. Thus, citrate competes with oxalate ion for binding to calcium cations. These conditions decrease the amount of free calcium ions available to form calcium oxalate crystals. In case of protein (mucin), however, the results suggest that no significant effect could be measured of mucin on nucleation and crystal growth.

Ischemic vaso-occlusive retinopathy as an initial manifestation is rare in pediatric systemic lupus erythematosus (pSLE). A 13-year-old girl presented with two months' history of papules and crusts with fatigue, weight loss, and abrupt hair loss. Pancytopenia and findings compatible with SLE, including positive direct Coombs' test, antinuclear antibody (Ab), anti-double stranded DNA Ab, anti-Smith Ab, anti-ribonucleoprotein Ab, lupus anticoagulant, anti-β2 glycoprotein Immunoglobulin G, and anti-cardiolipin Ab, were detected. Bi-nasal hemianopsia was detected. Initial visual acuity was hand motion in the right eye and 15/20 in the left. Fundoscopy showed massive exudation around the optic disc with macular edema, vascular sheathing with perivascular hemorrhage in the whole retina, and ghost vessels in the peripheral retina. Intravitreal triamcinolone injection and dexamethasone implant injection were administered. Visual symptoms improved but did not recover. Methylprednisolone therapy and photocoagulation improved visual acuity and fever. Early intervention for retinopathy in pSLE can help prevent vision-loss.