Robert Westwood

Dihydroorotate Dehydrogenase Is a High Affinity Binding Protein for A77 1726 and Mediator of a Range of Biological Effects of the Immunomodulatory Compound

A protein with high affinity (K 12 nM) for the immunomodulatory compound A77 1726 has been isolated from mouse spleen and identified as the mitochondrial enzyme dihydroorotate dehydrogenase (EC 1.3.3.1). The purified protein had a pI 9.6-9.8 and a subunit M of 43,000. Peptides derived from the mouse protein displayed high microsequence similarity to human and rat dihydroorotate dehydrogenase with, respectively, 35 and 39 out of 43 identified amino acids identical. Dihydroorotate dehydrogenase catalyzes the fourth step in de novo pyrimidine biosynthesis. The in vitro antiproliferative effects of A77 1726 are mediated by enzyme inhibition and can be overcome by addition of exogenous uridine. The rank order of potency of A77 1726 and its analogues in binding or enzyme inhibition was similar to that for inhibition of the mouse delayed type hypersensitivity response. It is proposed that inhibition of dihydroorotate dehydrogenase is an in vivo mechanism of action of the A77 1726 class of compounds. This was confirmed using uridine to counteract inhibition of the murine acute graft versus host response.

Treatment With Neutralizing Antibodies Specific for IL-1β Prevents Cyclophosphamide-Induced Diabetes in Nonobese Diabetic Mice

Interleukin-1 (IL-1) has been shown to be involved in the pathogenesis of IDDM, but it is not clear which form, IL-1α or IL-1β, is predominantly implicated. In this study, we have evaluated the contribution of IL-1β by treating diabetes-prone nonobese diabetic (NOD) mice with specific neutralizing antibodies. First, we assessed the neutralizing potential of these antibodies in C57BL/6 mice under acute septic shock by measuring IL-1β in sera 4 h after lipopolysaccharide injection. One milligram and 0.1 mg of anti–IL-1β antibodies (Abs) were capable of neutralizing the IL-1β produced, and the effect persisted for at least 5 days. Second, we evaluated the role of IL-1β in the cyclophosphamide (CY)-accelerated model of diabetes. Nondiabetic male NOD mice were injected with 200 mg/kg CY and treated twice weekly with anti–IL-1β Ab. The incidence of diabetes reached 76 and 100% in the control groups treated with 0.25 and 0.1 mg rabbit IgG, respectively. In contrast, only 34% of mice treated with 0.25 mg of anti–IL-1β Ab became diabetic. In the group treated with 0.1 mg of anti–IL-1β Ab, 89% of the mice became diabetic in the same period of time, demonstrating that the protective effect was dose dependent. Our results show that IL-1β is a critical effector molecule in this model of IDDM and that its specific inhibition could be an attractive target for therapeutic intervention.

1,3-dipolar cycloadditions of 2-ethoxy- and 2-(ethylthio)-1-azetines with nitrile oxides, nitrile ylides and nitrilimines : an unexpected 1,2,4-triazole formation

Abstract 2-Ethoxy- and 2-(ethylthio)-1-azetines readily undergo 1,3-dipolar cycloadditions with nitrile oxides and nitrile ylides to give stable 4,5-bicyclic cycloadducts. With nitrilimines, however, the expected 1,3-dipolar cycloadducts and/or unexpected ring-opened products, namely 1,2,4-triazoles, are formed depending on the nature of the nitrilimine N -substituent. In contrast, the azetines fail to react with nitrile sulphides, azomethine ylides, nitrones, aryl azides, and various dienes. X-ray crystallographic data on the nitrile oxide, nitrile ylide, and nitrilimine cycloadducts, and on the 1,2,4-triazoles, are presented. Also a mechanistic rationale for triazole formation is offered.

1,3-Dipolar cycloadditions of 2-ethoxy- and 2-(ethylthio)-1-azetines with nitrilimines

Abstract 1,3-Dipolar cycloadditions of diphenylnitrilimines with 2EtO-and 2EtS-tetramethyl-1-azetines (1a,b) are accompanied by ring-opening and loss of EtXH (X = O or S) to give 1,2,4-triazoles (3), whereas with N-(4-nitrophenyl) nitrilimines the expected cycloadducts and/or ring-opened products are formed.

2-(1,2-Dihydro-3-oxo-4,5-diphenyl-3H-pyrrol-2-ylidene)-1,2-dihydro-4,5-diphenyl-3H-pyrrol-3-one: A new pyrrole-based indigotin analogue

Abstract Thermolysis, in boiling o-dichlorobenzene, of the cycloadducts 5 and 10a,b of diphenylcyclopropenone and 2-(alkylthio)azetines 4 and 9a,b yield the title compound 8.