Copolymerization of N-4-Dibenzoylmethane Maleimide with Styrene

The copolymer of N-4-dibenzoylmethane maleimide (p-DBMI) with styrene (St) was prepared and characterized by gel permeation chromatography, thermal analysis and spectroscopy.

Induction of Mitochondrial Pathways and Endoplasmic Reticulum Stress for Increasing Apoptosis in Ectopic and Orthotopic Neuroblastoma Xenografts

Cancers are characterized by deregulation of multiple signaling pathways and thus monotherapies are hardly effective. Neuroblastoma, which often occurs in adrenal glands, is the most common childhood malignancy. Malignant neuroblastoma resists traditional treatments and further studies are needed for effective therapeutic interventions. We evaluated synergistic efficacy of N-(4-hydroxyphenyl) retinamide (4-HPR) and genistein (GST) for induction of apoptosis in human malignant neuroblastoma SH-SY5Y and SK-N-BE2 cells in culture and activation of multiple pathways for increasing apoptosis in ectopic and orthotopic neuroblastoma xenografts in nude mice. Combination of 4-HPR and GST synergistically reduced cell viability, caused subG1 accumulation, increased caspase-3 activity for apoptosis in vitro and reduced tumor growth in vivo. Western blotting indicated that combination therapy down regulated Id2 to induce differentiation, increased pro-apoptotic Bax and decreased anti-apoptotic Bcl-2 leading to an increase in Bax:Bcl-2 ratio, increased mitochondrial Bax level, caused mitochondrial release of Smac/Diablo, down regulation of the baculovirus inhibitor-of-apoptosis repeat containing (BIRC) proteins such as BIRC-2 and BIRC-3, and activation of calpain and caspase-3 in SH-SY5Y xenografts. Accumulation of apoptosis-inducing-factor (AIF) in cytosol and increase in caspase-4 activation suggested involvement of mitochondrial pathway and endoplasmic reticulum (ER) stress, respectively, for apoptosis in SH-SY5Y xenografts. In situ immunofluorescent labelings of SH-SY5Y and SK-N-BE2 xenograft sections showed overexpression of calpain, caspase-12, and caspase-3, and AIF, suggesting induction of mitochondrial caspase-dependent and caspase-independent pathways for apoptosis. Collectively, synergistic effects of 4-HPR and GST induced mitochondrial pathways and also ER stress for increasing apoptosis in ectopic and orthotopic neuroblastoma xenografts in nude mice.

Role of dihydroceramides in the progression of acute-on-chronic liver failure in rats

Background:Previously,dihydroceramide(d18:0/24:0)(dhCer(d18:0/24:0))was reported to be a potential biomarker for acute-onchronic liver failure(ACLF)prognosis.In this study,we further explored the role of dhCer(d18:0/24:0)in the progression of ACLF to validate the biomarker using ACLF rat model.Methods:ACLF rats were sacrificed at 4 and 8 h post-D-galactosamine(D-gal)/lipopolysaccharide(LPS)administration to investigate the liver biochemical markers,prothrombin time and liver histopathology.Change in dhCer and other sphingolipids levels were investigated by high-performance liquid chromatography coupled to tandem mass spectrometry(HPLC-MS/MS).Rats were treated with N-(4-hydroxyphenyl)retinamide(4-HPR)to examine the mortality rate and its role in improving ACLF.Results:LPS/D-gal administration resulted in significant elevation in alanine aminotransferase(ALT)and aspartate aminotransferase(AST)levels.Prothrombin time was prolonged and histopathological examination showed abnormality.HPLC-MS/MS results showed total dhCer levels in ACLF group(64.10±8.90 pmol/100 mL,64.22±6.78 pmol/100 mL for 4 and 8 h,respectively)were decreased significantly compared with control group(121.61±23.09 pmol/100 mL)(P<0.05).In particular,dhCer(d18:0/24:0),dhCer(d18:0/20:0),and dhCer(d18:0/22:0)levels were decreased.Treatment with 4-HPR significantly increased the levels of dhCers,including dhCer(d18:0/24:0)compared with ACLF group,for the level of dhCer(d18:0/24:0)in 4-HPR group was 20.10±8.60 pmol/100 mL and the level of dhCer(d18:0/24:0)in ACLF group was 9.74±2.99 pmol/100 mL(P<0.05).This was associated with reduced mortality rate and prolonged survival time.The ALT and AST in 4-HPR group were significantly decreased compared with ACLF group.The prothrombin time of 4-HPR group(41.49 s)was significantly lower than the prothrombin time of ACLF group(57.96 s)(P<0.05).4-HPR also decreased plasma ammonia levels slightly,as the plasma ammonia levels in 4-HPR group and ACLF group were 207.37±60.43,209.15±60.43 mmol/L,respectively.Further,4-HPR treatment improved histopathological parameters.Conclusions:DhCer,especially dhCer(d18:0/24:0),is involved in the progression of ACLF.Increasing the levels of dhCer can reduce the mortality rate of ACLF rats and alleviate liver injury.