Browsing by Author "Amit Kumar Ray"

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Blood-Central Nervous System Barriers in Morphine Dependence and Withdrawal
(Elsevier Inc., 2004) Hari Shanker Sharma; Ranjana Patnaik; Amit Kumar Ray; Prasanta Kumardey
The status of blood-central nervous system barriers during morphine dependence or withdrawal is still unknown. Morphine withdrawal is associated with profound stress response, immediate early gene expression in the CNS and alterations in neurochemical metabolism. Thus, a possibility exists that stress caused by morphine withdrawal will impair blood-CNS barriers function. Experiments carried out in our laboratory show that spontaneous morphine withdrawal in rats is associated with a selective and specific breakdown of the blood-brain, blood-CSF and blood-spinal cord barriers to Evans blue albumin, radioactive iodine and lanthanum (La3+) tracers. Several brain regions show pronounced structural alterations during morphine dependence and withdrawal. Pharmacological manipulations of nitric oxide (NO), serotonin (5-hydroxytryptamine) or Ca2+ channel during morphine dependence and withdrawal attenuates the blood-CNS barrier dysfunction and structural changes. These observations suggest that morphine dependence and withdrawal is associated with alterations in CNS microfluid environment and cellular damage. The functional significance of these findings and the probable mechanisms are discussed. © 2004 Elsevier Inc. All rights reserved.
Chronic exercise alters EEG power spectra in an animal model of depression
(1996) Suptendra Nath Sarbadhikari; Sangita Dey; Amit Kumar Ray
The EEG from frontal cortex, EMG and EEG were recorded from rats exposed to only exercise (Treadmill), only stress, exercise + stress and neither (control). In comparison with the control group, the percent of Delta activity in the awake was significantly increased in the depressed group and significantly decreased in the exercised groups, while for Beta-2, the reverse occurred; Theta increased and Beta-2 decreased in the NREM sleep state of the depressed group and the opposite happened for the exercised groups; Delta and Alpha-2 activity significantly increased in the depressed group, and they were significantly decreased in the exercised groups whereas the Beta-2 activity showed contrary changes in the REM sleep state. These findings indicate that exercise has the opposite effect from what stress has on qEEG and concomitant physical exercise reduces the effects of stress. Behavioral tests were done by Open Field (OF) and High Plus Maze (HPM). Slow EEG activity (Delta, Theta, Alpha) was significantly positively correlated with immobilization in the OF and defecation in both OF and HPM and negatively with the food intake, transfer latency in HPM; rearing, grooming and total ambulation in OF. Whereas, fast activity (Beta-2) was significantly negatively correlated with immobilization in OF and defecation in OF and HPM, while positively with ambulation in the central squares of OF and time spent at the central cross and number of times arms crossed in the HPM.
Mangiferin as chain transfer agent: effect on the molecular weight of poly(methyl methacrylate) and polystyrene
(Springer Verlag, 2015) Shilpa Jaiswal; Kalyan Ramesh; Govinda Kapusetti; Amit Kumar Ray; Biswajit Ray; Nira Misra
Abstract: Free radical polymerization of methyl methacrylate (MMA) and styrene (St) has been performed in N,N-dimethylformamide (DMF) at 70 °C in the presence of varying concentration of mangiferin as chain transfer agent using 2,2′-azobisisobutyronitrile (AIBN) as initiator. With increase in mangiferin concentration, molecular weight of the obtained polySt gradually decreases as expected due to the chain transfer phenomenon, but that of polyMMA interestingly increases possibly due to the preferential auto-acceleration phenomenon during MMA polymerization in the presence of higher concentration of mangiferin. The observed chain transfer constant of mangiferin for styrene polymerization is 0.14. The incorporation of mangiferin in the resultant polymers is confirmed by FTIR and UV–Vis studies.; Graphical abstract: [Figure not available: see fulltext.] © 2015, Springer-Verlag Berlin Heidelberg.