The wild type insulin-like growth factor I (IGF-I) receptor has both mitogenic and transforming activities. We have examined the effect of point mutations at tyrosine residues 1250 and 1251 on these two properties of the receptor. For this purpose, we stably transfected plasmids expressing mutant and wild type receptors into R ؊ cells, which are 3T3-like cells, derived from mouse embryos with a targeted disruption of the IGF-I receptor genes, and therefore devoid of endogenous IGF-I receptors. A tyrosine to phenylalanine mutation of either the 1250 or 1251 residue, or both, has no effect on the ability of the receptor to transmit a mitogenic signal. However, the tyrosine 1251 mutant receptor and the double mutant have lost the ability to transform R ؊ cells (colony formation in soft agar), even when the receptors are expressed at very high levels, while the Y1250F mutant is fully transforming. These experiments show that the 1251 tyrosine residue is required for the transforming activity of the IGF-I receptor.

Nitric oxide (NO) deficiency has been implicated in many pathological and physiological processes within the mammalian body providing a plausible biologic basis for the use of NO replacement therapy in these conditions. Exogenous NO sources may hopefully constitute a powerful way to supplement NO when the body cannot generate enough for normal biological functions. This theory has opened up the possibility of designing new drugs that are capable of delivering NO into tissues and the bloodstream in a sustained and controlled manner. This objective has been reached by grafting an organic nitrate structure onto existing molecules with various spacers such as aliphatic or aromatic chain, with different degree of complexity. This approach has led to the synthesis of several new chemical entities in various pharmacological classes, whose profile seems to challenge the parent drug not only on the basis of new pharmacological properties but also on a better toxicological and safety profile. In this article, general aspects on NO and NO donors are reviewed. Major focus is placed upon recent developments of novel NO donors, NO releasing device(s) as well as innovative improvements to conventional NO donors. Several examples are given in some important therapeutic indications such as cardiovascular diseases (NO-aspirin), pain and inflammation (NO-paracetamol), osteoporosis and urinary incontinence (NO flurbiprofen with aliphatic spacer), Alzheimer s disease (NO-flurbiprofen with anti-oxidant spacer), respiratory disorders (NO-steroids).

Nitric oxide (NO) deficiency has been implicated in many pathologic processes, thus providing a solid biological basis for the use of NO replacement therapy. Exogenous NO sources constitute a powerful way to supplement NO when the body cannot generate sufficient NO for normal biological functions. This theory has opened up the possibility of designing new drugs that are capable of delivering NO into tissues and the bloodstream in a sustained and controlled manner. This objective has been achieved by grafting an organic nitrate structure onto existing drugs through chemical spacers, such as aliphatic, aromatic, or a heterocyclic chain. The approach has led to the synthesis of several new chemical entities whose pharmacologic profile challenges the parent drug, not only on the basis of new properties, but also with respect to a better safety profile. In this article, a specific class of NO donors is reviewed, the nitric oxide-releasing non-steroidal antiinflammatory drugs, NO-NSAIDs. Recently discovered compounds, whose action depends on the combined properties of both the known drug and NO release, are illustrated. Two examples are described in detail: (1) nitric oxide-releasing aspirin, which has demonstrable innovative properties for treatment of vascular disorders and cancer; (2) nitro-derivatives of flurbiprofen that have shown encouraging results in models of Alzheimer's disease.

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