We have found that N-acetylneuraminic acid (NANA) consumes toxic hydrogen peroxide (H 2 O 2 ) under physiological conditions. Close investigation of this ¢nding revealed that NANA was oxidized by an equimolar amount of H 2 O 2 to provide its decarboxylated product, 4-(acetylamino)-2,4-dideoxy-D-glycero-D-galacto-octonic acid (ADOA). To date, there have been little data on this reaction, and its physiological signi¢cance has not been discussed. Examining the detoxi¢cation of H 2 O 2 in cultured cells with NANA, we were able to con¢rm that the cell death caused by H 2 O 2 was suppressed by NANA in a dose-dependent manner. These results revealed a novel role for NANA as a reactive oxygen scavenger. It is known that terminal NANA residues are removed by neuraminidase and that free NANA molecules are recycled or degraded by enzymes. We propose that released monomeric NANA is the potent defense molecule against oxidative damage.

A new concept for catalytic reactions in aqueous media is demonstrated by using a temperature‐responsive polymer support, poly(N‐alkylacrylamide), which is converted into a catalyst by assembly with phosphotungstic acid. At high temperature, the catalyst is highly active in the oxidation of alcohols with H2O2 owing to the formation of emulsions, whereas the product and catalyst are easily separated at low temperature (see scheme).

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Hirschsprung's disease (HSCR) is a congenital intestinal disease, characterized by the absence of ganglion cells in the distal portion of the intestinal tract. Recently, three susceptibility genes have been identified in HSCR, namely the RET protooncogene, the endothelin B (ET B ) receptor gene (EDNRB), and the endothelin-3 (ET-3) gene (EDN3). To investigate whether mutations in EDNRB could be related with HSCR in non-inbred populations in Japan, we examined alterations of the gene in 31 isolated patients. Three novel mutations were detected as follows: two transversions, A to T and C to A at nucleotides 311 (N104I) and 1170 (S390R), respectively, and a transition, T to C at nucleotide 325 (C109R). To analyze functions of these mutant receptors, they were expressed in Chinese hamster ovary cells. S390R mutation did not change the binding affinities but caused the decreases in the ligand-induced increment of intracellular calcium and in the inhibition of adenylyl cyclase activity, showing the impairment of the intracellular signaling. C109R receptors were proved to be localized near the nuclei as an unusual 44-kDa protein with the extremely low affinity to endothelin-1 (ET-1) and not to be translocated into the plasma membrane. On the other hand, N104I receptors showed almost the same binding affinities and functional properties as those of the wild type. Therefore, we conclude that S390R and C109R mutations could cause HSCR but that N104I mutation might be polymorphous. Hirschsprung's disease (HSCR)1 is a congenital intestinal disorder, characterized by the absence of ganglion cells in the distal portion of the intestinal tract, as a consequence of premature arrest of cranio-caudal migration of neural crest cells. Recently, three susceptibility genes have been identified in HSCR, namely the RET protooncogene, the endothelin B (ET B ) receptor gene (EDNRB), and the endothelin-3 (ET-3) gene (EDN3).Mice with targeted null disruption of Ret exhibited an autosomal recessive phenotype comprising the total lack of the enteric nervous system and renal agenesis (1), that provided an excellent model of HSCR. Approximately 50 mutations in RET have so far been identified, and the RET mutations account for 50% of familial and 15-20% of sporadic cases of HSCR, over 75% of which are associated with long segment HSCR (2-6).Endothelins (ETs) are a family of 21 amino acid vasoactive peptides, consisting of three isopeptides, ET-1, ET-2 and ET-3, that act on G protein-coupled receptors, ET A and ET B (7-11). ET A exhibits different affinities to the three isopeptides in the order of ET-1 Ն ET-2 Ͼ Ͼ ET-3. ET B accepts all three isopeptides equally. These receptors regulate multiple effector pathways, for example, phospholipase C via G q , and adenylyl cyclase via G s in smooth muscle cells (ET A ), and via G i in endothelial cells (ET B ) (12, 13). Mice with targeted null disruption of either Ednrb or Edn3 exhibit an identical phenotype, coat color spotting, and aganglionic megacolon, similar to HSCR or Shah-Waardenburg syndrome in...

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