Showing papers by "Sudip Dey published in 2011"

Experimental infection of pigs with group A rotavirus and enterotoxigenic Escherichia coli in India: gross, histopathological and immunopathological study.

Abstract: The authors describe a detailed study conducted in Assam, India, of gross, histopathological and immunopathological alterations in pigs experimentally infected with rotavirus and enterotoxigenic Escherichia coli (ETEC) expressing K88 pili. A total of 30 Caesarean derived piglets were infected experimentally with rotavirus alone or in combination with ETEC to study the gross and histopathological alterations and the distribution pattern of different B- and T cell subsets in the gut. Villus atrophy, especially in the jejunum and ileum, was the consistent lesion in piglets infected with rotavirus, while in piglets simultaneously infected with rotavirus and ETEC, severe necrosis of the intestinal villi was observed. Ultrastructural studies revealed similar pathological alterations in the ileum of the infected piglets. A morphometric study of the intestinal villi and crypts showed a reduction in the ratio between the average villus height and crypt depth (VH:CD ratio) in the group infected with rotavirus (5.95±0.33) and those infected with rotavirus and ETEC (7.90±0.16). A higher (p<0.01) reduction in the VH:CD ratio was observed in the jejunum (8.83±0.79) and ileum (8.46±0.78) compared that in the duodenum (10.03±0.50) of the infected pigs. Piglets infected with rotavirus and sacrificed on day 6 post infection revealed the presence of lymphocytes containing cytoplasmic IgA+ (cIgA+) cells in the villus lamina propria and intra-epithelial CD8+ T cells in the villus epithelia. Rotavirus infection of young piglets in association with ETEC was more severe than rotavirus infection alone. Such infection resulted in marked clinico-pathological and immunological alterations in the infected piglets.

Surface ultrastructure of larval mouthpart sensilla of the muga silkmoth, Antheraea assamensis, an endemic species of North-East India.

Abstract: Scanning electron microscopy of different larval stages of the muga silk moth Antheraea assamensis revealed the presence of sensilla chaetica, sensilla trichoidea, sensilla styloconica, gustatory sensilla, sensory pegs, placoid sensilla, etc., on their mouth parts. Some variations were observed in the number and sub-types of sensilla in certain larval stages indicating some differences in sensitivity of the worms in different instars to the food plant and microhabitat. Microsc. Res. Tech., 2010. © 2010 Wiley-Liss, Inc.

An electron microscopic analysis on the ultra structural abnormalities in sperm of the common carp Cyprinus carpio L. inhabiting a polluted lake, Umiam (Meghalaya, India).

Abstract: The present communication reports the ultra structural abnormalities in sperm of a fish species Cyprinus carpio inhabiting a polluted lake, Umiam in North-East India. Transmission electron microscopy (TEM) revealed absence of differentiation between head and midpiece (neck) of some sperm while scanning electron microscopy (SEM) showed some sperm tails with highly reduced length and some sperm with folded tail. Abnormal shape of some sperm head was also revealed by Scanning electron microscopy. Detachment of membrane from some parts of the sperm head and an outward expansion of the same was observed from Transmission electron micrographs of transverse section of sperm head. The well developed mitochondria surrounding the cytoplasmic channel in the sperm tail, as observed in control were found to be drastically disorganized in fish inhabiting the polluted lake. The study suggests that the fish C. carpio inhabiting the polluted lake Umiam is under severe stress as far as its male reproductive system is concerned. The study further suggests that Electron microscopic approach is extremely important in the assessment of adverse effects of environmental pollution on fish tissue. Microsc. Res. Tech. 2011. © 2011 Wiley Periodicals, Inc.

Free Vibration of Delaminated Composite Shallow Conical Shells

Abstract: This paper presents a finite element method to investigate the effects of delamination on free vibration characteristics of graphite-epoxy pretwisted shallow angle-ply composite conical shells The generalized dynamic equilibrium equation is derived from Lagrange's equation of motion neglecting Coriolis effect for moderate rotational speeds The theoretical formulation is exercised by using an eight noded isoparametric plate bending element based on Mindlin's theory Multi-point constraint algorithm is utilized to ensure the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front The standard eigen value problem is solved by applying the QR iteration algorithm Finite element codes are developed to obtain numerical results concerning the effect of twist angle, location of delamination and rotational speed on natural frequencies of delaminated angle-ply composite conical shells The mode shapes are also depicted for a typical laminate configuration Parametric studies of symmetric and anti-symmetric angle-ply laminates provide the non-dimensional natural frequencies which are the first known results for the type of analyses carried out here

UV-reflecting wing scales in the silk moth Antheraea assamensis: its biophysical implications.

Abstract: Scanning electron microcopy of the wing scales from some specific locations in the silk moth, Antheraea assamensis, revealed the presence of 50–60-nm-thick microridges and 80-nm-thick air spaces between them The principle of optics suggests that when the measured average thickness of microridges or lamellae is about 50–60 nm, that of the air-space between them is about 80–82 nm, then due to the known refractive index of air (10) and the infrared refractive index of lamellar cuticle (160), the lamellae (microridges) and the intervening lamellar air spaces will have similar optical thickness A common optical thickness for the two types of layers causes the microridge structures to function in the fashion of a quarter wavelength interference filter and to reflect UV light Behavioral studies under the natural conditions and short experimental exposure of the moths to artificial UV light suggests that coupling behavior of the moth is governed to a significant extent by these UV-reflecting wing scales The importance of the study in overcoming a major problem of low autocoupling efficiency of moths in the Muga Silk Industry is discussed with the help of relevant literature Microsc Res Tech 74:28-35, 2011 © 2010 Wiley-Liss, Inc

Scanning electron microscopic studies on thoracic sensilla of different larval stages in the 'muga' silk moth, antheraea assamensis, and their role in feeding behaviour

Abstract: Le papillon du ver a soie muga Antheraea assamensis est une espece originaire de l'Assam et d'autres Etats du nord-est de l'Inde. Bien que l'on pense que des connaissances detaillees du systeme sensoriel de l'insecte soient importantes pour mettre au point des strategies appropriees pour son elevage et sa domestication, il existe tres peu de rapports sur l'etude des aspects ultrastructuraux ou de base du systeme sensoriel de l'insecte. Dans le cadre de nos etudes sur le systeme sensoriel larvaire du ver a soie muga Antheraea assamensis, cet article fournit une description detaillee sur la morphologie, les caracteristiques ultrastructurales de la surface, l'emplacement, le profil de distribution, etc. de differentes sensilles thoraciques pendant tous les stades larvaires. On a pu detecter un ensemble de sensilles y compris, une plage setifere de sensilles, des sensilles trichoides, basiconiques, des sensilles a sillons, des sensilles campaniformes, etc. a differents emplacements du thorax. Nous discutons du role possible de ces sensilles dans le comportement de recherche du ver pendant l'alimentation a l'aide de la litterature appropriee.