Studies on lipid peroxidation in pancreatic tissue. In vitro formation of thiobarbituric-acid-reactive substances (TBRS)

Hydrogen-rich water regulates effects of ROS balance on morphology, growth and secondary metabolism via glutathione peroxidase in Ganoderma lucidum

Ganoderma lucidum is one of the most important medicinal fungi, but the lack of basic study on the fungus has hindered the further development of its value. To investigate the roles of the redox system in G. lucidum, acetic acid (HAc) was applied as a reactive oxygen species (ROS) stress inducer, and hydrogen-rich water (HRW) was used to relieve the ROS stress in this study. Our results demonstrate that the treatment of 5% HRW significantly decreased the ROS content, maintained biomass and polar growth morphology of mycelium, and decreased secondary metabolism under HAc-induced oxidative stress. Furthermore, the roles of HRW were largely dependent on restoring the glutathione system under HAc stress in G. lucidum. To provide further evidence, we used two glutathione peroxidase (GPX)-defective strains, the gpxi strain, the mercaptosuccinic acid (MS, a GPX inhibitor)-treated wide-type (WT) strain, and gpx overexpression strains for further research. The results show that HRW was unable to relieve the HAc-induced ROS overproduction, decreased biomass, mycelium morphology change and increased secondary metabolism biosynthesis in the absence of GPX function. The gpx overexpression strains exhibited resistance to HAc-induced oxidative stress. Thus, we propose that HRW regulates morphology, growth and secondary metabolism via glutathione peroxidase under HAc stress in the fungus G. lucidum. Furthermore, our research also provides a method to study the ROS system in other fungi.

Calcium and reactive oxygen species in acute pancreatitis: friend or foe?

SIGNIFICANCE

Acute pancreatitis (AP) is a debilitating and, at times, lethal inflammatory disease, the causes and progression of which are incompletely understood. Disruption of Ca(2+) homeostasis in response to precipitants of AP leads to loss of mitochondrial integrity and cellular necrosis.

RECENT ADVANCES

While oxidative stress has been implicated as a major player in the pathogenesis of this disease, its precise roles remain to be defined. Recent developments are challenging the perception of reactive oxygen species (ROS) as nonspecific cytotoxic agents, suggesting that ROS promote apoptosis that may play a vital protective role in cellular stress since necrosis is avoided.

CRITICAL ISSUES

Fresh clinical findings have indicated that antioxidant treatment does not ameliorate AP and may actually worsen the outcome. This review explores the complex links between cellular Ca(2+) signaling and the intracellular redox environment, with particular relevance to AP.

FUTURE DIRECTIONS

Recent publications have underlined the importance of both Ca(2+) and ROS within the pathogenesis of AP, particularly in the determination of cell fate. Future research should elucidate the subtle interplay between Ca(2+) and redox mechanisms that operate to modulate mitochondrial function, with a view to devising strategies for the preservation of organellar function.

Influence of bile acids on stimulated lipid peroxidation and hydrogen peroxide production in rat liver microsomes

Bile acids were found to be effective antioxidants in bile and intestine. The influence of different bile acids on the NADPH-Fe(++)-stimulated lipid peroxidation (LPO) and cytochrome P-450 dependent hydrogen peroxide production (H2O2) in rat liver microsomes was investigated in vitro. LPO was determined as production of thiobarbituric acid reactants (TBAR). Different tri-, di- and monohydroxylated bile acids and cholesterol were given to the incubation mixture in concentrations ranging from 10(-5) to 10(-3) M. Sodium salts of cholic, tauroglycocholic and deoxycholic acids as well as cheno-deoxycholic, ursodeoxycholic, lithocholic acids and cholesterol did not alter the microsomal production of TBAR. H2O2 formation was significantly decreased by sodium deoxycholate whereas cholesterol increased H2O2 production up to 4 times. These results show that bile acids were not able to protect microsomal membrane lipids against peroxidative damage. Cholesterol mediated H2O2 formation as a source of hydroxyl radicals had no toxic effect concerning LPO, TBAR were not enhanced significantly.

Influence of trypsin-induced acute pancreatitis on survival and energy state of isolated acinar cells from rat pancreas

To study the development of acute pancreatitis after intraductal trypsin instillation, at 4 hours, 1, 2, 4 and 6 days after this treatment and after instillation of physiologic saline viable acinar cells were isolated from rat pancreas. Gross anatomic and histologic findings were used to evaluate the time course of pathomorphologic changes. The isolated cells were incubated at 37 degrees C in Eagle's medium in a shaking water bath and the time course of their damage was studied. Additionally, by means of the active accumulation of the fluorophore rhodamine 6 G alterations of the mitochondrial membrane potential, an important parameter of the cellular energy metabolism was evaluated. The most severe histological damage was seen 1 and 2 days after trypsin instillation. At the same time yield and survivability of cells isolated, and their mitochondrial membrane potential reached a minimum. In the controls the time course of these parameters was very similar, but their decrease was less pronounced. Since a direct action of trypsin on acinar cells cannot be responsible for the findings presented a possible involvement of inflammatory cells and their products in the alteration of the cells and of their energy metabolism must be considered.