Regulation on Calcium Oxalate Crystallization and Protection on HK-2 Cells of Tea Polysaccharides with Different Molecular Weights.

The regulation on calcium oxalate (CaOx) crystallization and protective effect on human proximal tubular epithelial cells (HK-2) of four green tea polysaccharides (TPSs) with molecular weights of 10.88 (TPS0), 8.16 (TPS1), 4.82 (TPS2), and 2.3 kDa (TPS3) were comparatively studied. XRD, Fourier transform infrared spectroscopy, and scanning electron microscopy results revealed that TPS1, TPS2, and TPS3 can increase the percentage of the dihydrate crystalline phase in CaOx crystals and reduce the size of CaOx monohydrate crystals. TPSs increased the absolute value of the zeta potential of CaOx crystal and inhibited crystal nucleation and aggregation. The nucleation inhibition rates of TPS1, TPS2, and TPS3 to CaOx crystallization were 56.67%, 75.52%, and 52.92%, respectively, and their aggregation inhibition rates were 22.34%, 47.59%, and 21.59%, respectively. TPS preprotection can alleviate the oxidative damage of HK-2 cells caused by oxalate, increase cell viability, protect cell morphology, and reduce lactate dehydrogenase release and reactive oxygen species levels. The degraded TSPs, especially TPS2 with moderate molecular weight, may be used as a green drug to inhibit stone formation.

Nanouric acid or nanocalcium phosphate as central nidus to induce calcium oxalate stone formation: a high-resolution transmission electron microscopy study on urinary nanocrystallites.

PURPOSE: This study aimed to accurately analyze the relationship between calcium oxalate (CaOx) stone formation and the components of urinary nanocrystallites. METHOD: High-resolution transmission electron microscopy (HRTEM), selected area electron diffraction, fast Fourier transformation of HRTEM, and energy dispersive X-ray spectroscopy were performed to analyze the components of these nanocrystallites. RESULTS: The main components of CaOx stones are calcium oxalate monohydrate and a small amount of dehydrate, while those of urinary nanocrystallites are calcium oxalate monohydrate, uric acid, and calcium phosphate. The mechanism of formation of CaOx stones was discussed based on the components of urinary nanocrystallites. CONCLUSION: The formation of CaOx stones is closely related both to the properties of urinary nanocrystallites and to the urinary components. The combination of HRTEM, fast Fourier transformation, selected area electron diffraction, and energy dispersive X-ray spectroscopy could be accurately performed to analyze the components of single urinary nanocrystallites. This result provides evidence for nanouric acid and/or nanocalcium phosphate crystallites as the central nidus to induce CaOx stone formation.

Renal epithelial cell injury and its promoting role in formation of calcium oxalate monohydrate.

The injurious effect of hydrogen peroxide (H(2)O(2)) on renal epithelial cells of the African green monkey (Vero cells) and the difference in the modulation of Vero cells on crystal growth of calcium oxalate (CaOxa) before and after injury were investigated. The degree of injury of Vero cells was proportional to the concentration and action time of H(2)O(2). After the cells had been injured, the released amount of malonaldehyde in the culture medium increased, the superoxide dismutase activity decreased, the expression quantity of osteopontin on the surface of Vero cells increased significantly, the zeta potential became more negative, and the amount of CaOxa crystals adhering to cells increased. The CaOxa crystals induced by the cells in the control group were round and blunt; however, those induced by the injured cells had irregular shapes with sharp edges and corners. As the crystallization time increased from 6 to 24 h, the size of the crystals induced by the injured cells increased accordingly, whereas that of crystals induced by the control cells did not increase significantly. The injured cells could promote the growth of CaOxa crystals and their adhesion to the cells; thus, the formation of CaOxa stones was promoted. The cells in the control group could also be injured after being incubated with supersaturated CaOxa solution for a long time, which promoted the crystallization of CaOxa. The results suggest that the retention of supersaturated CaOxa solution or CaOxa crystals in the urinary tract for a long time is a risk factor for the formation of kidney stones.