Phagocytosis of senescent erythrocytes by autologous monocytes: requirement of membrane-specific autologous IgG for immune elimination of aging red blood cells

The role of membrane-bound IgG present on the membrane of senescent erythrocytes in immune eliminations of aging red cells was investigated. Phagocytosis of populations of red blood cells (RBC) of different ages by autologous monocytes was assessed both by direct phagocytosis and by induction of microsomal heme oxygenase. Removal of IgG from older RBCs inhibited their phagocytosis; in contrast, preincubation of neuraminidase-treated young or in vitro aged RBCs with IgG eluted from old cells led to phagocytosis of RBCs treated by autologous monocytes. It was also found that the Fc portion of membrane-bound IgG is essential for the elimination of senescent cells; less than 15% of old heat-inactivated RBCs coated with F(ab)2 fragment of membrane-bound IgG were phagocytosed. In contrast, more than 50% of old heat-inactivated RBCs coated with heat-eluted IgG were phagocytosed by autologous monocytes. A possible mechanism of elimination of aged cells is discussed.     

Prey of the Persian Leopard (Panthera pardus saxicolor) in a mixed forest-steppe landscape in northeastern Iran (Mammalia: Felidae)

We carried out a dietary analysis of Persian Leopards, Panthera pardus saxicolor, in a temperate region in north-eastern Iran, where the largest population nucleus exists across the subspecies range. We investigated 113 faecal samples collected between February 2009 and March 2010 in Golestan National Park. Faecal analysis revealed that leopards predominantly preyed upon wild ungulates, with the Wild Boar, Sus scrofa, being the most important prey species in terms of frequency and biomass. Eleven different prey items were identified, 7 of which were ungulates, comprising 99% of the total food items. We also found a spatial pattern in the prey composition of leopards: cervids were predominantly found in forest landscapes, whereas Wild Sheep, Ovis orientalis, was mainly found in steppe habitats, revealing the leopards’ predation on medium-to large-sized ungulates. Livestock remains were mainly extracted from steppe samples, but the overall contribution to the leopard diet pattern (approximately 8.5% of consumed biomass) suggested that conflict with human communities, at least within the investigated core parts of the National Park, is not a major concern. The study provides the first illustration of the Persian Leopard's dietary composition in a temperate area with a relatively high diversity of available prey, and can be a baseline for future investigation and human-leopard interaction monitoring     

Brain microdialysis and its applications in experimental neurochemistry

Microdialysis is one of the most powerful neurochemistry techniques, which allows the monitoring of changes in the extracellular content of endogenous and exogenous substances in the brain of living animals. The strength as well as wide applicability of this experimental approach are based on the bulk theory of brain neurotransmission. This methodological review introduces basic principles of chemical neurotransmission and emphasizes the difference in neurotransmission types. Clear understanding of their significance and degree of engagement in regulation of physiological processes is an ultimate prerequisite not only for choosing an appropriate method of monitoring for interneuronal communication via chemical messengers but also for accurate data interpretation. The focus on the processes of synthesis/metabolism, receptor interaction/ neuronal signaling or the behavioral relevance of neurochemical events sculpts the experiment design. Brain microdialysis is an important method for examining changes in the content of any substances, irrespective of their origin, in living animals. This article compares contemporary approaches and techniques that are used for monitoring neurotransmission (including in vivo brain microdialysis, voltammetric methods, etc). We highlight practical aspects of microdialysis experiments in particular to those researchers who are seeking to increase the repertoire of their experimental techniques with brain microdialysis.     

The role of PNP enzyme in autologous rosette-forming cells

Since purine nucleoside phosphorylase has been associated with suppressor function in lymphocytes, enzyme activities were studied in autologous rosette-forming cells, a subset showing suppressor properties. Levels of this enzyme were higher in these cells than in other T cells. Con A induction of autologous red cell receptors and suppressor activity of T cells were both inhibited in dose-dependent fashion by Formycin B, a well known inhibitor of purine nucleoside phosphorylase. Inhibition of autologous rosette-forming cells was obtained after pulse treatment of cells with Formycin B for as little as 1 hr, whereas cell proliferation was only inhibited when Formycin B was present throughout culture; this confirms the independence of cell proliferation, and development of red cell receptors and suppressor activity. This study indicates a crucial role for purine nucleoside phosphorylase enzyme in induction of T cell suppressor activity.