Browsing by Author "A.K. Ray"

Now showing 1 - 8 of 8

Anterior cerebellum as a site for morphine analgesia and post-stimulation analgesia
(1982) P.K. Dey; A.K. Ray
[No abstract available]
Bamboo - A functionally graded composite-correlation between microstructure and mechanical strength
(2005) A.K. Ray; S. Mondal; S.K. Das; P. Ramachandrarao
Bamboo is supposed to be one of the best functionally gradient composite materials available. In a piece of bamboo, not only the number of fibres ('vascular bundles') but also the fibre quality varies from outer to inner-most periphery. It has been observed that near the outer periphery, within 1 mm 2 area, the number of fibres is approximately 8 whereas the same at the inner-most periphery is approximately 2. Again the cross-sectional shape of fibre at outer periphery is almost circular (diameter 0.14 mm) and compacted but at the inner-most periphery, a fibre (diameter of major axis 0.93 × diameter of minor axis 0.78 mm) has been sprayed, and contain matrix in it. This structural behaviour causes the variation of tensile strength, e.g., the strength of a fibre at the outer periphery is about 160 kg/mm2 and the same at the inner-most periphery is only 45 kg/mm2. It has also been observed that the matrix of bamboo can preferentially be removed from the fibre by alkali treatment. 10% NaOH can remove adhered matrix with little effect on fibres while 20% or stronger alkali reduces the strength of fibre. © 2005 Springer Science + Business Media, Inc.
Cerebral oedema and blood-brain and blood-CSF barriers in experimental brain trauma: Effect of indomethacin - a prostaglandin synthetase inhibitor
(1980) S. Mohanty; A.K. Ray; P.K. Dey
[No abstract available]
Influence of glycyl-proline (a dipeptide sequence of β-LPH at 43-44 position) on central actions of morphine
(1982) A.K. Ray; P.K. Dey
An endogenous dipeptide, located in 43-44 position of β - LPH chain, markedly antagonises morphine analgesia in rats but has no effect on morphine catatonia. A dose of 50 ug/100 g body weight of it shows about 80% antagonism. The site of its antagonistic action appears to be on the ventral surface of the brain stem. This dipeptide has further been shown to markedly facilitate the development of tolerance to morphine analgesia. Structure-activity relationship of this dipeptide demonstrates that the cationic amino group of glycine and hydrophobic moiety of proline are essential for exhibiting antagonism against morphine analgesia. © 1982.
Microstructural characterization of bamboo
(2004) A.K. Ray; S.K. Das; S. Mondal; P. Ramachandrarao
The microstructural properties of bamboo were analyzed. A typical bamboo specimen was air dried in open atmosphere after collection and then cut into small pieces. The microstructural characterization of the gold coated bamboo specimen were carried out using scanning electron microscope (SEM). The fracture of the vascular bundle show that the fibers contains many sclerenchyma cells. The wall thickness in between two sclerenchyma cells ranges from 1 to 5 μm and the width of the same varies from 10 to 20 μm.
Morphine analgesia following its infusion into different liquor spaces in rat brain
(1980) A.K. Ray; P.K. Dey
Infusion of morphine (1 μg) into the lateral ventricle, fourth ventricle, subarachnoid space beneath the brainstem, and cisterna magna, produces analgesia. The analgesia was tested with tail-flick response with radiant heat stimulus. Of all the liquor spaces, the structures on the ventral surface of the brainstem caudal to the fossa interpeduncularis appear to be the most sensitive site for the antinciceptive action of morphine. The possible explanation for the analgesic action elicited from the ventral surface of the brainstem is discussed.
The role of serotonin in cerebral oedema
(1979) S. Mohanty; P.K. Dey; A.K. Ray
[No abstract available]
Zinc protoporphyrin IX attenuates closed head injury-induced edema formation, blood-brain barrier disruption, and serotonin levels in the rat
(Springer-Verlag Wien, 2006) P. Vannemreddy; A.K. Ray; R. Patnaik; S. Patnaik; S. Mohanty; H.S. Sharma
The role of heme oxygenase (HO) in closed head injury (CHI) was examined using a potent HO and guanylyl cyclase inhibitor, zinc protoporphyrin (Zn-PP) in the rat. Blood-brain barrier (BBB) permeability to Evans blue and radioiodine, edema formation, and plasma and brain levels of serotonin were measured in control, CHI, and Zn-PP-treated CHI rats. CHI was produced by an impact of 0.224 N on the right parietal bone by dropping 114.6 g weight from a height of 20 cm in anesthetized rats. This concussive injury resulted in edema formation and brain swelling 5 hours after insult that was most pronounced in the contralateral hemisphere. The whole brain was edematous and remained in a semi-fluid state. Microvascular permeability disturbances to protein tracers were prominent in both cerebral hemispheres and the underlying cerebral structures. Plasma and brain serotonin showed pronounced increases and correlated with edema formation. Pretreatment with Zn-PP (10 mg/ kg, i.p) 30 minutes before or after CHI attenuated edema formation, brain swelling, plasma and brain serotonin levels, and microvascular permeability at 5 hours. Brain edema, BBB permeability, and serotonin levels were not attenuated when the compound was administered 60 minutes post-CHI suggesting that HO is involved in cellular and molecular mechanisms of edema formation and BBB breakdown early after CHI. © 2006 Springer-Verlag.