Direct synthesis of amino-functionalized monodispersed mesoporous silica spheres and their catalytic activity for nitroaldol condensation

New amino-functionalized monodispersed mesoporous silica spheres (MMSS) were synthesized directly by co-condensation of 3-aminopropyltrimethoxysilane (AP-TMS), [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAP-TMS) or 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AEAEAP-TMS) with tetramethoxysilane. By changing the methanol ratio or adding extra silica source, amino-functionalized MMSS with different particle diameter (310–780 nm) and the same mesopore size were successfully synthesized. TEM observations revealed that the mesopores were aligned radially from the center towards the outside of the spheres even in the amino-functionalized MMSS. The effect of particle diameter on base catalytic activity was investigated using the amino-functionalized MMSS. In addition, the amino-functionalized MMSS were found to be excellent base catalysts in the nitroaldol condensation reactions. The effectiveness factor was evaluated to be 0.8–0.82 and improved substantially compared with MMSS prepared by grafting method.     

Screening and diagnosis of beta-ureidopropionase deficiency by gas chromatographic/mass spectrometric analysis of urine

Dihydropyrimidine dehydrogenase (DHPDase), dihydropyrimidinase (DHPase) and beta-ureidopropionase (betaUPase) are the enzymes that catalyze the first, second, and third steps of the degradation of pyrimidines, respectively. beta-Ureidopropionate (betaUP) and beta-ureidoisobutyrate (betaUIB) are increased in the urine of patients with betaUPase deficiency. The original case in which betaUPase deficiency was discovered by NMR spectroscopy was an 11-month-old patient who presented with hypotonia and dystonic movement. We detected a second but asymptomatic case during a pilot study of neonatal screening with filter-paper urine, urease pretreatment and gas chromatography/mass spectrometry (GC/MS). The urease pretreatment of urine without fractionation resulted in a high recovery of these polar ureide compounds and allowed the highly sensitive GC/MS detection and diagnosis of betaUPase deficiency. betaUP and betaUIB were identified using GC/MS techniques. In the urine of the neonate with betaUPase deficiency, betaUP and betaUIB were persistently increased. Thymine, 5,6-dihydrothymine and 5,6-dihydrouracil were increased only moderately but significantly. It is known that thymine and uracil increase markedly in DHPDase deficiency, and 5,6-dihydrothymine and 5,6-dihydrouracil increase in DHPase deficiency. Therefore, betaUPase deficiency can be differentially diagnosed from the first and second enzyme deficiencies. Application of this specific and sensitive diagnostic procedure will lead to an understanding of the clinical heterogeneity of betaUPase deficiency. Furthermore, the identification of patients with defects in pyrimidine metabolism will enable doctors to avoid cancer chemotherapy with pyrimidine analogues such as 5-fluorouracil, which could be dangerous for these patients.