Adrenergic and serotonergic function in dna synthesis during rat liver regeneration and in hepatocyte cultures

The adult mammalian liver is predominantly in a quiescent state with respect to cell division. This quiescent state changes dramatically, however, if the liver is injured by toxic, infectious or mechanic agents (Ponder, 1996). Partial hepatectomy (PH) which consists of surgical removal of two-thirds of the liver, has been used to stimulate hepatocyte proliferation (Higgins & Anderson 1931). This experimental model of liver regeneration has been the target of many studies to probe the mechanisms responsible for liver cell growth control (Michalopoulos, 1990; Taub, 1996). After PH most of the remaining cells in the renmant liver respond with co-ordinated waves of DNA synthesis and divide in a process called compensatory hyperplasia. Hence, liver regeneration is a model of relatively synchronous cell cycle progression in vivo. In contrast to hepatomas, cell division is terminated under some intrinsic control when the original cellular mass has been regained. This has made liver regeneration a useful model to dissect the biochemical and molecular mechanisms of cell division regulation. The liver is thus, one of the few adult organs that demonstrates a physiological growth rewonse (Fausto & Mead, 1989; Fausto & Webber, 1994). The regulation of liver cell proliferation involves circulating or intrahepatic factors that are involved in either the priming of hepatocytes to enter the cell cycle (Go to G1) or progression through the cell cycle. In order to understand the basis of liver regeneration it is mandatory to define the mechanisms which (a) trigger division, (b) allow the liver to concurrently grow and maintain dilferentiated fimction and (c) terminate cell proliferation once the liver has reached the appropriate mass. Studies on these aspects of liver regeneration will provide basic insight of cell growth and dilferentiation, liver diseases like viral hepatitis, toxic damage and liver transplant where regeneration of the liver is essential. In the present study, Go/G1/S transition of hepatocytes re-entering the cell cycle after PH was studied with special emphasis on the involvement of neurotransmitters, their receptors and second messenger function in the control of cell division during liver regeneration

Fenneropenaeus indicus is protected from white spot disease by oral administration of inactivated white spot syndrome virus

Fenneropenaeus indicus could be protected from white spot disease (WSD) caused by white spot syndrome virus (WSSV) using a formalin-inactivated viral preparation (IVP) derived from WSSV-infected shrimp tissue. The lowest test quantity of lyophilized IVP coated onto feed at 0.025 g–1 (dry weight) and administered at a rate of 0.035 g feed g–1 body weight d–1 for 7 consecutive days was sufficient to provide protection from WSD for a short period (10 d after cessation of IVP administration). Shrimp that survived challenges on the 5th and 10th days after cessation of IVP administration survived repeated challenges although they were sometimes positive for the presence of WSSV by a polymerase chain reaction (PCR) assay specific for WSSV. These results suggest that F. indicus can be protected from WSD by simple oral administration of IVP