Fas (Apo-1/CD95) is a cell-surface receptor involved in cell death signaling. The key role of the Fas system in negative growth regulation has been studied mostly within the immune system, and somatic mutations of Fas gene in cancer patients have been described solely in lymphoid-lineage malignancies. However, many nonlymphoid tumor cells have been found to be resistant to Fas-mediated apoptosis, which suggests that Fas mutations, one of the possible mechanisms for Fas resistance, may be involved in the pathogenesis of nonlymphoid malignancies as well. In this study, we have analyzed the entire coding region and all splice sites of the Fas gene for the detection of the gene mutations in 44 human malignant melanomas in skin by polymerase chain reaction, single-strand conformation polymorphism, and DNA sequencing. Overall, 3 tumors (6.8%) were found to have the Fas mutations, which were all missense variants and identified in the cytoplasmic region (death domain) known to be involved in the transduction of an apoptotic signal. The data presented here suggest that somatic alterations of the Fas gene might lead to the loss of its apoptotic function and contribute to the pathogenesis of some human malignant melanomas.

This review summarizes the synthesis of various pyrazoles reported by us and some other research groups in 1981–1989.

This review introduces the synthesis of various pyrazoles reported by us and some other research groups during 1989–1998. Some of papers in this review deal with the development of potent pyrazoles or with the synthesis of potential pyrazoles aiming at agrochemicals and/or drugs.

This review describes the 1,3‐dipolar cycloaddition reaction, deoxygenation, deoxygenative transformation, ring transformation and photochemical reaction of quinoxaline N‐oxides and N,N′‐dioxides.

The reaction of the alkylhydrazinoquinoxaline N‐oxides 2a‐d with dimethyl acetylenedicarboxylate gave the dimethyl 1‐alkyl‐1,5‐dihydropyridazino[3,4‐b]qumoxaline‐3,4‐dicarboxylates 3a‐d, whose reaction with nitrous acid effected the C4‐oxidation to afford the dimethyl 1‐alkyl‐4‐hydroxy‐1,4‐dihydropyridazino‐[3,4‐b]quinoxaline‐3,4‐dicarboxylates 4a‐d, respectively. The reaction of compounds 4a‐d with 1,8‐diazabicyclo[5.4.0]‐7‐undecene in ethanol provided the ethyl 1‐alkyl‐4‐oxo‐1,4‐dihydropyridazino[3,4‐b]quinoxa‐line‐3‐carboxylates 5a‐d, while the reaction of compounds 4a‐d with potassium hydroxide furnished the 1‐alkyl‐4‐oxo‐1,4‐dihydropyridazino[3,4‐b]quinoxaline‐3‐carboxylic acids 6a‐d, respectively. Compounds 6c,d were also obtained by the reaction of compounds 5c,d with potassium hydroxide, respectively.