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Kumar, Rahul

Publications and source records attributed to Kumar, Rahul.

21 records · Page 2

IS THE GALACTIC COSMIC-RAY SPECTRUM CONSTANT IN TIME?

The hypothesis is considered that the present, local Galactic cosmic-ray spectrum is, due to source intermittency, softer than average over time and over the Galaxy. Measurements of muogenic nuclides underground could provide an independent measurement of the time-averaged spectrum. Source intermittency could also account for the surprising low anisotropy reported by the IceCube Collaboration. Predictions for Galactic emission of ultrahigh-energy (UHE) quanta, such as UHE gamma rays and neutrinos, might be higher or lower than previously estimated.

79 ASTRONOMY AND ASTROPHYSICS↗

Role of mitogen activated protein kinases in skin tumorigenicity of Patulin

WHO has highlighted the need to evaluate dermal toxicity of mycotoxins including Patulin (PAT), detected in several fruits. In this study the skin carcinogenic potential of topically applied PAT was investigated. Single topical application of PAT (400 nmol) showed enhanced cell proliferation ({approx} 2 fold), along with increased generation of ROS and activation of ERK, p38 and JNK MAPKs, in mouse skin. PAT exposure also showed activation of downstream target proteins, c-fos, c-Jun and NF-{kappa}B transcription factors. Further, single topical application of PAT (400 nmol) followed by twice weekly application of TPA resulted in tumor formation after 14 weeks, indicating the tumor initiating activity of PAT. However no tumors were observed when PAT was used either as a complete carcinogen (80 nmol) or as a tumor promoter (20 nmol and 40 nmol) for 25 weeks. Histopathological findings of tumors found in PAT/TPA treated mice showed that these tumors were of squamous cell carcinoma type and similar to those found in the positive control group (DMBA/TPA) along with significant increase of lipid peroxidation and decrease in free sulfydryls, catalase, superoxide dismutase and glutathione reductase activities. The results suggest the possible role of free radicals in PAT mediated dermal tumorigenicity involving MAPKs. -- Highlights: Black-Right-Pointing-Pointer Single topical application of Patulin showed enhanced cell proliferation. Black-Right-Pointing-Pointer Patulin activate MAPKs, c-fos, c-Jun and NF-{kappa}B transcription factors. Black-Right-Pointing-Pointer Patulin showed skin tumor initiating potential. Black-Right-Pointing-Pointer We could not detect skin tumor promoting potential of Patulin at the tested dose. Black-Right-Pointing-Pointer However prolonged exposure of Patulin at a higher dose may promote tumor.

60 APPLIED LIFE SCIENCES↗