Enzymatic synthesis of M(1)G-deoxyribose.

Adducts formed between electrophiles and nucleic acid bases are believed to play a key role in chemically induced mutations and cancer. M(1)G-dR is an endogenous exocyclic DNA adduct formed by the reaction of the dicarbonyl compound malondialdehyde with a dG residue in DNA. It is an intermediate in the synthesis of a class of modified oligodeoxyribonucleotides that are used to study the mutagenicity and repair of M(1)G.

Structural analysis of UDP-sugar binding to UDP-galactose 4-epimerase from Escherichia coli.

UDP-galactose 4-epimerase from Escherichia coli catalyzes the interconversion of UDP-galactose and UDP-glucose through the transient reduction of the tightly bound cofactor NAD+. The enzyme is unique among the NAD+-dependent enzymes in that it promotes stereospecific reduction of the cofactor but nonstereospecific hydride return during normal catalysis. In addition to hydride transfer, the reaction mechanism of epimerase involves two key features: the abstraction of a proton from the 4'-hydroxyl group of glucose or galactose by an active site base and the rotation of a 4-ketopyranose intermediate in the active site pocket.

[Singular diaphragm-like colonic stricture and short-term administration of a non-steroidal anti-inflammatory drug].

A case of diaphragm-like stricture of the colon induced by non steroidal anti-inflammatory drug (diclofénac LP) is reported in a 65-year-old man who presented abdominal pain. Colonoscopy revealed ulcer in the transverse right colon. The patient gradually developed diaphragm-like stricture in the transverse right colon.

[Nephroblastoma with symptomatic neuronal differentiation].

We report the anatomoclinical analysis of a child with a renal tumor: the preoperative diagnosis was neuroblastoma, because of elevated dopamine urinary excretion and positive MIBG scintigraphy. The histopathological and immunohistochemical analysis revealed a prominent neural differentiation in a multicystic nephroblastoma. This observation recalls the Masson's proposed neuroectodermal histogenesis of Wilms tumor; however the currently accepted metanephrogenic blastematous origin is not reconsidered.