GM2 gangliosidosis associated with a HEXA missense mutation in Japanese Chin dogs: A potential model for Tay Sachs disease

GM2 gangliosidosis is a fatal lysosomal storage disease caused by a deficiency of β-hexosaminidase (EC 3.2.1.52). There are two major isoforms of the enzyme: hexosaminidase A composed of an α and a β subunit (encoded by HEXA and HEXB genes, respectively); and, hexosaminidase B composed of two β subunits. Hexosaminidase A requires an activator protein encoded by GM2A to catabolize GM2 ganglioside, but even in the absence of the activator protein, it can hydrolyze the synthetic substrates commonly used to assess enzyme activity. GM2 gangliosidosis has been reported in Japanese Chin dogs, and we identified the disease in two related Japanese Chin dogs based on clinical signs, histopathology and elevated brain GM2 gangliosides. As in previous reports, we found normal or elevated hexosaminidase activity when measured with the synthetic substrates. This suggested that the canine disease is analogous to human AB variant of G_M2 gangliosidosis, which results from mutations in GM2A. However, only common neutral single nucleotide polymorphisms were found upon sequence analysis of the canine ortholog of GM2A from the affected Japanese Chins. When the same DNA samples were used to sequence HEXA, we identified a homozygous HEXA:c967G>A transition which predicts a p.E323K substitution. The glutamyl moiety at 323 is known to make an essential contribution to the active site of hexosaminidase A, and none of the 128 normal Japanese Chins and 92 normal dogs of other breeds that we tested was homozygous for HEXA:c967A. Thus it appears that the HEXA:c967G>A transition is responsible for the GM2 gangliosidosis in Japanese Chins.     

50th anniversary of the discovery of ibuprofen: an interview with Dr Stewart Adams

2011 marks the 50th anniversary of the discovery of ibuprofen. This article is a focus on the personal reflections and career of Dr Stewart Adams OBE, the scientist whose research lead to the discovery of the cyclooxygenase inhibitor. When Dr Adams discovered ibuprofen, he was working as a pharmacologist in the Research Department for the Boots Pure Drug Company Ltd. Dr Adams was assigned to work on rheumatoid arthritis (RA) and chose in 1953 to search for a drug that would be effective in RA but would not be a corticosteroid. He was one of the first workers in this field that later became known as NSAIDs (Non-Steroidal Anti Inflammatory Drugs). In 1961, Dr Adams with John Nicholson, the organic chemist, filed a patent for the compound 2-(4-isobutylphenyl) propionic acid, later to become one of the most successful NSAIDs in the modern world, ibuprofen. In this article, Dr Adams gives his modest insight into the early stages and initial observations which led to this world-wide success.