A New Discovery of Calcium Phosphate Urinary Stones Formation Induced by Melamine: Nanocrystalline Assembly Mechanism

Investigations on melamine-based uric acid kidney stone formation and its prevention by inhibitors

Melamine (Mel) as a milk powder adulterant came to light in September 2008, when a kidney stone disease (KSD) outbreak struck China. The mechanism of the formation of Mel-associated uric acid (UA) stones is relatively unknown. Therefore, in the present study, Mel's influence was explored at comparatively higher and lower concentrations in artificial urine. The parameter optimization performed when the Mel concentration in artificial urine was low, which revealed that higher pH values and lower UA concentration considerably delayed the induction of UA crystallization. When Mel concentration was increased relative to UA concentration, the induction time of UA crystallization decreased dramatically. At the highest concentration of Mel investigated (at UA-Mel molar ratio 1:1), PXRD analysis and SEM revealed a change in crystalline structure of the samples. Based on FTIR analysis, it was determined that UA-Mel interactions are essentially physical, because no new characteristic bands developed. Two inhibitors, namely tri-potassium citrate (TPC) and 3, 7-dimethylxanthine (DMX), were investigated for their inhibitory action on UA crystallization in the presence of Mel. DMX was observed to be more promising than TPC in delaying the induction of crystallisation and hence inhibiting crystal formation.

Enantioselective Peroxidation of C-Alkynyl Imines Enabled by Chiral BINOL Calcium Phosphate

Herein, we reported a catalytic enantioselective addition of C-alkynyl imines with hydroperoxides catalyzd by chiral BINOL calcium phosphate, affording a broad range of enantioenriched α-peroxy propargylamines in good yields (80-99%)...

Rate-controlled nano-layered assembly mechanism of melamine-induced melamine–uric acid stones and its inhibition and elimination methods

The formation of kidney stones induced by melamine is a rate-controlled nano-scale supramolecular layered assembly process.