Cytokine activation of phosphoinositide 3-kinase sensitizes hematopoietic cells to cisplatin-induced death

Cytokine growth factors regulate the normal proliferation of hematopoietic cells but can also override irradiation-induced growth arrest checkpoints through activation of a phosphoinositide 3-kinase (PI3K) signaling pathway. In the present study, we assessed the effect that erythropoietin and interleukin-3 have on cisplatin-treated hematopoietic cells. When cultured in the presence of cytokine, cisplatin-treated 32D cells transiently accumulated in a G(2)-M phase arrest and ultimately died by a nonapoptotic mechanism. By comparison, reduction of cytokine-induced PI3K activity, either through cytokine receptor mutation or direct inhibition with LY294002, caused cisplatin-treated cells to enter a biphasic G(1) and G(2)-M arrest. The arrest of these cells coincided with an absence of cyclin-dependent kinase (Cdk)1 and Cdk2 activity and significantly reduced cell death during cisplatin treatment. Indeed, LY294002 treatment during cisplatin exposure allowed the recovery of a viable, proliferating cell population after removal of cisplatin. In contrast, Cdks remained active in the G(2)-M-arrested population of cisplatin-treated cells with continuous cytokine activation of PI3K, and even transient exposure to cisplatin resulted in death of the entire population. These data suggest that cytokine activation of PI3K signaling pathways overrides cisplatin-induced growth arrest checkpoints, thereby sensitizing hematopoietic cells to DNA damage-induced death.     

Synthesis and antibacterial activity of some 5-guanylhydrazone/thiocyanato-6-arylimidazo[2,1-b]-1,3, 4-thiadiazole-2-sulfonamide derivatives

6-Arylimidazo[2,1-b]-1,3,4-thiadiazole-2-sulfonamides 3 on Vilsmeier-Haak reaction produced 5-formyl-6-arylimidazo[2,1-b]-1,3, 4-thiadiazole-2-[N-(dimethylaminomethino)]sulfonamides 4, while 3 on treatment with potassium thiocyanate in the presence of bromine in acetic acid produced 5-thiocyanato-2-sulfonamides 6. Interaction of 4 with aminoguanidine hydrochloride in ethanol produced the corresponding 5-guanylhydrazone derivatives 5. Compounds 5 and 6 showed a high degree of antibacterial activity against both Escherichia coli and Staphylococcus aureus comparable to that of sulfamethoxazole and Norfloxacin. However, they were found to show moderate activity against Salmonella typhi, Pseudomonas aeruginosa and Pneumococci.     

Acalvaria

Acalvaria is a rare congenital malformation in which the flat bones of the cranial vault, duramater and associated muscles are absent but the central nervous system is usually unaffected. Acalvaria has usually been described as a fatal anomaly and reports are rare in the Indian literature. We report a living case of acalvaria.