Catalase Activity in Rice Shoot Apex during Panicle Initiation

There was a gradual increase in the catalase activity in theshoot apices of the two rice varieties—Ratna and BAM 11,till panicle initiation. Peroxide content in the Ratna shootapices decreased with time and was low during and after panicleinitiation. In Ratna plants, exogenous application of cycloheximideand 3-amino-1,2,4-triazole resulted in a delay in panicle initiationwith a corresponding decrease in catalase activity. Exogenousapplication of hydrogen peroxide caused a rise in catalase activityand delayed panicle initiation in both Ratna and BAM 11 varieties.In BAM 11 plants treated with 28 consecutive short photoinductivecycles there was an earliness in flowering accompanied by anearly peak in catalase activity. (Received May 10, 1985; Accepted August 12, 1985)     

Glassy dynamics in the folding landscape of cytochrome c detected by laser photolysis

Ferrocytochrome c liganded with CO refolds to a nativelike compact state, called the M state, where the non-native Fe2+-CO contact persists. The M state resembles the generic molten globule-like states and can be driven to the native state by pulsed laser photolysis of the CO ligand. The microsecond kinetics measured all across the guanidine hydrochloride unfolding transition of the protein produce a chevron plot with accentuated rollover in the folding limb, suggesting a glass transition of M en route to N. The rate of exit of the folding structure from the kinetic trap(s) limits the overall rate of folding of M to N. Sulfate-induced deceleration of the observed folding rate suggests that the folding structure indeed is transiently frozen in glassy traps. The results connect the post-transition features of the funnel paradigm.     

Novel 1,4-dihydropyridine induces apoptosis in human cancer cells through overexpression of Sirtuin1

1,4-Dihydropyridines (1,4-DHPs) are important as a class of heterocyclic compounds that exhibit wide range of biological actions. Many of its derivatives are already characterized as medicinally important drugs and used worldwide. In this study, we have screened some novel Hantzsch 1,4-DHP compounds using both in silico (QSAR and Pharmacophore) and in vitro (cytotoxic screening). 1,4-DHP showed selective cytotoxicity against five human cancerous cell lines; A375, A549, HeLa, HepG2 and SH-SY5Y but limited effect towards normal skin keratinocyte (HaCaT), lung fibroblast (WL-38) and healthy peripheral blood mononuclear cells. In A375 and HepG2 cells, one of the 1,4-DHP derivative (DHP-8) was found to inhibit cell proliferation, and simultaneously increased the apoptotic population as well as mitochondrial membrane depolarization. Furthermore, the mitochondrial signal was triggered with the activation of cleaved Caspase9, Caspase3 and PARP. The treatment with DHP-8 also increased the expression level of SIRT1, subsequently decreasing the level of pAKT^ser473 and survivin. Reduced pAKT^ser473 expression led to decrease the phosphorylated inactive form of GSK3β^ser9 and as a result, proteasomal degradation of Mcl-1 occurred in both the cell lines. Here, we suggest that the apoptotic effect of DHP-8 in A375 and HepG2 cells was mediated by AKT and survivin pathways through SIRT1 activation. The involvement of DHP-8 in SIRT1 activation was further verified by co-treatment of nicotinamide with DHP-8 in both A375 and HepG2 cells. Overall, this study emphasizes the possible potential and therapeutic role of DHP-8 in skin and liver cancer.     

Antioxidant and anticataractogenic effects of topical captopril in diquat-induced cataract in rabbits.

1-[(2s)-3-Mercapto-2-methylpropionyl]-L-proline (captopril), an antihypertensive and free radical scavenger, protected the rabbit lens from peroxidative and oxidative damage induced by 1 mM diquat in vitro. To evaluate the anticataract efficacy of captopril, an experimental group of five rabbits was treated with topical captopril (1% in 0.15 M NaCl, w/v), and 50 microliters was instilled onto both eyes four times a day for a total of 8 weeks. Following the same procedure, the eyes of five rabbits were treated with topical 0.15 M NaCl as a control for captopril treatment. At the end of the first week of treatment, a single intravitreal dose of 120 nmole diquat in 30 microliters of 0.15 M NaCl was injected into the right eye of each rabbit of both the groups. As a control for intravitreal diquat injection, the left eye of all the rabbits were injected with the diluent, 30 microliters per eye. The intravitreal diquat or its diluent injection was only for one time. From slit-lamp biomicroscopic observation of the diquat-injected right eyes, the anticataract effect of captopril in the treatment group was indicated by the finding that in four of five rabbits the cataract did not advance; whereas in four of five rabbits treated with the diluent the cataract progressed to grade 3. The lenses in the diluent-injected control left eyes of the rabbits treated with the captopril or diluent were normal. However, since the number of animals used for the in vivo studies was few, further confirmation of the anticataract effect of captopril is necessary. In diquat-injected right eyes of animals treated with captopril, the integrated rate of O2- production was about 50% less (p less than .001) in the aqueous humor, vitreous humor, and lens, compared with O2-, 33.49 +/- 2.26 microM (mean +/- SEM) in the aqueous humor, 17.12 +/- 0.75 microM in the vitreous humor, and 31.44 +/- 1.29 nmole/g wet weight in the lens of the diquat-injected right eyes treated with the diluent. Similar significant (p less than .01) differences in the production of .OH and H2O2 in eye tissues were also observed.(ABSTRACT TRUNCATED AT 400 WORDS)