Biomedical subjects

Dimitrios J Kondomerkos

Publications and source records attributed to Dimitrios J Kondomerkos.

4 recordsLinked to original sources

PubMed2005

Effects of adrenergic agents on rat peritoneal macrophages activated in vitro by acetylated low-density lipoprotein.

Macrophages interact with modified lipoproteins and alter their functional status. In this study, the effects of the adrenergic agents adrenaline, isoproterenol, and dobutamine on macrophages activated with acetylated low-density lipoprotein were tested. The aim of this investigation was to determine whether adrenergic agents influence biologically significant functions of these cells in an in vitro model of macrophage-lipoprotein acute interaction. Rat peritoneal macrophages were incubated with acetylated low-density lipoprotein for 16 h, with or without adrenergic agents. Hydrogen peroxide and nitric oxide production and acid phosphatase activities in the supernatant and cell lysate were assayed. Adrenaline and isoproterenol inhibited the production of hydrogen peroxide, stimulated the production of nitric oxide, and increased the extracellular activity of acid phosphatase in the lipoprotein-activated cells. Dobutamine increased the extracellular, but decreased the intracellular acid phosphatase activity. Adrenaline and dobutamine also produced changes in the cell size and nuclear morphology of the macrophages. Macrophages are activated in vitro by acetylated low-density lipoprotein, and their functions and morphology are modified under the influence of adrenergic agents. Certain effects could be attributed to changes in cyclic AMP levels.

Acid Phosphatase↗

PubMed2004

Glycogen autophagy.

Glycogen autophagy, which includes the sequestration and degradation of cell glycogen in the autophagic vacuoles, is a selective process under conditions of demand for the massive hepatic production of glucose, as in the postnatal period. It represents a link between autophagy and glycogen metabolism. The formation of autophagic vacuoles in the hepatocytes of newborn animals is spatially and biochemically related to the degradation of cell glycogen. Many molecular elements and signaling pathways including the cyclic AMP/cyclic AMP-dependent protein kinase and the phosphoinositides/TOR pathways are implicated in the control of this process. These two pathways may converge on the same target to regulate glycogen autophagy.

Animals↗

PubMedDate not supplied

Effects of cyclic AMP-elevating hormones and autacoids on LPS-activated rat peritoneal, bronchoalveolar and hepatic (Kupffer) macrophages.

Peritoneal, bronchoalveolar and hepatic (Kupffer) macrophages activated in vitro by endotoxin, exhibit alterations in nitric oxide production when certain hormones or other biologically active agents (autacoids) are present in the culture medium. They also show changes in acid beta-glucuronidase activities and morphological changes concerning cell size and general appearance. Agents known to elevate the intracellular levels of cyclic AMP, e.g. adrenalin, prostaglandin E2 and dopamine, increase the nitric oxide production in all three types of macrophage. The addition of H-89, an inhibitor of protein kinase A, abolishes the increase in nitric oxide production. Adrenalin also increases the extracellular activity of beta-glucuronidase. The results of this work suggest that cyclic AMP-elevating hormones and autacoids affect the functions of endotoxin-activated macrophages, such as the production of nitric oxide and the activity of acid beta-glucuronidase.

Animals↗

PubMedDate not supplied

The effects of phosphoinositide/calcium- or cyclic AMP-mediated signal transduction pathway inhibitors on the activation of rat peritoneal macrophages by acetylated low-density lipoprotein.

BACKGROUND: Macrophages that uptake modified lipoproteins are activated and may initially behave as endotoxin-stimulated macrophages. This study was undertaken in order to determine whether signal transduction pathways controlling endotoxin-mediated activation may also influence the lipoprotein-mediated activation of macrophages. MATERIALS AND METHODS: Rat peritoneal macrophages were incubated for 16 hours with acetylated low-density lipoprotein and certain agents that modify the phosphoinositide/calcium- and cyclic AMP-mediated pathways, such as 2-[4-morpholinyl]-8-phenyl-1[4H]-benzopyran-4-one (LY-294002), autocamtide 2-related inhibitory peptide (AIP), N-(2-[p-bromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide hydrochloride (H-89) and actinomycin D. The production of nitric oxide and the intracellular and extracellular activities of acid phosphatase were assayed. RESULTS: Macrophages incubated with acetylated low-density lipoprotein showed an increased production of nitric oxide and intracellular acid phosphatase activity as compared to their controls. LY-294002, AIP and H-89 caused a significant decrease in nitric oxide production and intracellular acid phosphatase activity. Actinomycin D had similar effects. AIP and actinomycin also significantly increased extracellular acid phosphatase activity. CONCLUSION: The activation of peritoneal macrophages by acetylated low-density lipoprotein was similar to the activation by endotoxin, as expressed by the nitric oxide production and acid phosphatase intracellular activity; agents controlling the phosphoinositide/calcium- and cyclic AMP-mediated pathways in endotoxin-activated macrophages also influence the acetylated low-density lipoprotein-activated macrophages.

Acid Phosphatase↗