PubMed Health⌕ Search

Biomedical subjects

P Patriarca

Publications and source records attributed to P Patriarca.

At least 73 records · Page 4Linked to original sources
PubMed1976

Studies on the mechanism of metabolic stimulation in polymorphonuclear leukocytes during phagocytosis. Activators and inhibitors of the granule bound NADPH oxidase.

The effects of several known inhibitors and activators of peroxidase-catalyzed reactions have been studied on the NADPH oxidase activity of granules isolated from polymorphonuclear leukocytes at rest or during phagocytosis. Redogenic substances, such as ascorbate or hydroquinone, and superoxide dismutase, which are known to inhibit peroxidase-catalyzed reactions, also inhibited the NADPH oxidase activity of granules. Oxidogenic substances, such as guaiacol or resorcinol, and manganese, which are known to stimulate peroxidase-catalyzed reactions, also activated the NADPH oxidase activity of granules. Cyanide, an inhibitor of peroxidase-catalyzed reactions, inhibited the NADPH oxidase activity of granules isolated from resting leukocytes but only slightly affected that of granules isolated from phagocytosing cells, as previously reported. A list of the properties of the NADPH oxidase activity of granules and of peroxidase oxidase activity is given. The arguments in favor of and those against a possible identity of the two activities are discussed.

Animals↗
PubMed1976

Metabolic perturbation of the inflammatory cells.

An activation of the oxidative metabolism of phagocytes is a regular concomitant of phagocytosis as well as of other functions of these cells such as exocytosis, chemotactic locomotion, and immune-adherence. Several other substances, some of which may be found in the inflammatory site, are also able to stimulate the oxidative metabolism of phagocytes, for example phospholipases, antileucocyte antibodies, endotoxins, fatty acids, surfactants and fragments of complement. This paper deals with, (1) the molecular events occurring within the plasma membrane that trigger the stimulation of the oxidative metabolism. An experimental model is presented that involves redistribution of ions across the plasma membrane of leucocytes as the trigger of the stimulated respiration and exocytosis; (2) the intracellular localization of the enzymatic system that is the effector of the metabolic response. A scheme is proposed for the mechanism of this enzymatic system which accounts for the production of highly reactive compounds such as hydrogen peroxide, superoxide anion radical and hydroxyl radical during the metabolic activation of phagocytes.

Animals↗
PubMed1976

Influence of E. COLI POLysaccharide on the interaction of E. coli K+ and K- with polymorphonuclear leukocytes in vitro.

Both a K+ strain and a K- strain of E. coli withstand phagocytic killing by polymorphonuclear leukocytes and do not stimulate the respiratory burst, that accompanies phagocytosis in these cells, as compared with E. coli J 53 which are extensively and rapidly killed and stimulate the respiration of leukocytes. Both K+ and K- E. coli become readily phagocytosable after removal of their polysaccharide by heat treatment and are able to stimulate oxygen consumption by PMN. Heat treated E. coli J 53 stimulate the oxygen uptake of PMN less than live E. coli J 53. The polysaccharide extracted from either K+ or K- E. coli inhibits both phagocytosis of and the respiration stimulated by all the three heat-treated strains used. Instead the polysaccharide extracted from the phagocytosable strain J 53 stimulates the oxygen consumption of PMN exposed to the heat treated K- strain or heat treated J 53 itself.

Animals↗
PubMed1975

Studies on the mechanism of metabolic stimulation in polymorphonuclear leucocytes during phagocytosis. I. Evidence for superoxide anion involvement in the oxidation of NADPH2.

1. The oxidation of NADPH2 by leucocyte granules, as measured at acid pH in the presence of Mn-2+, was found to be inhibited by superoxide dismutase. 2. Omission of Mn-2+ markedly lowered the oxidase activity at acid pH, which was still inhibited by superoxide dismutase. 3. At alkaline pH the oxidase activity was lower than at acid pH. 4. During oxidation of NADPH2 by leucocyte granules, reduction of cytochrome c occurred which was partially inhibited by superoxide dismutase. 5. It was concluded that NADPH2 oxidation occurs through an enzymatic reaction and a nonenzymatic chain reaction. Superoxide anion (O-minus-2 and NADPH- free radical would be involved in the chain reaction. The differential sensitivity of NADPH2 oxidation to superoxide dismutase in different experimental conditions (see above 1, 2 and 3) was explained on the basis of changes in the properties of the chain reaction.

Animals↗
PubMed1975

Studies on the mechanism of metabolic stimulation in polymorphonuclear leucocytes during phagocytosis. II. Presence of the NADPH2 oxidizing activity in a myeloperoxidase-deficient subject.

1. The biochemical properties of leucocytes from a myeloperoxidase-deficient subject were compared with those of leucocytes from healthy subjects. 2. Myleoperoxidase-deficient leucocytes responded to phagocytosis of heat-killed bacteria with increased respiration, increased oxidation of glucose through the hexose monophosphate shunt and increased production of H2O2 as normal leucocytes do. 3. The ability of granules isolated from myeloperoxidase-deficient leucocytes to oxidize nicotinamide coenzymes was comparable to that of granules isolated from normal leucocytes. 4. The results argue against the hypothesis that oxidation of NADPH2 in leucocytes is performed by myeloperoxidase.

Adult↗
PubMed1975

Correlation between phagocytic activity and metabolic response of polymorphonuclear leukocytes toward different strains of Escherichia coli.

The bactericidal activity, the phagocytic capacity, and the metabolic stimulation of polymorphonuclear leukocytes challenged with different strains of Escherichia coli were studied. It was found that only two strains out of 10 tested stimulated the oxygen consumption and carbohydrate metabolism of leukocytes and were readily killed by the phagocytes. The lack of killing of the other eight strains was shown to be due to absent or poor phagocytosis rather than to resistance to intracellular killing. Evidence was presented that the surface K antigen plays an important role in conferring antiphagocytic properties to some strains of E. coli. It was suggested that K antigen acts by interfering with the early step of the phagocytic process, that is, the attachment step.

Animals↗
PubMed1974

Phospholipid metabolism by phagocytic cells. Phospholipases A2 associated with rabbit polymorphonuclear leukocyte granules.

Polymorphonuclear leukocytes obtained from sterile peritoneal exudates in rabbits contain two phospholipid-splitting activities (phosphatidylacylhydrolases EC 3.1.1.4), one most active at pH 5.5 and the other between pH 7.2 and 9.0. Hydrolysis of phospholipid was demonstrated using Escherichia coli labeled during growth with [1-(14)C]oleate and then autoclaved to inactivate E. coli phospholipases and to increase the accessibility of the microbial phospholipid substrates. The acid and alkaline phospholipase activities are both membrane bound, calcium dependent, and heat stable, and they appear to be specific for the 2-acyl position of phospholipids. Evidence was also obtained suggesting that the E. coli envelope phospholipids with oleate in position 2 are more readily degraded than those with palmitate. The two activities are associated with azurophilic as well as specific granules (obtained by zonal centrifugation) and with phagosomes (isolated after ingestion of paraffin particles by the granulocytes). Phospholipase A activities at pH 5.5 and pH 7.5 degrade the two major phospholipids of E. coli, phosphatidylethanolamine and phosphatidylglycerol, to the same extent, but the phospholipase activity at acid pH does not hydrolyze micellar dispersions of phosphatidylethanolamine. By contrast, phospholipase A(2) activity at pH 7.5 degrades both types of phosphatidylethanolamine substrates. Heparin and chondroitin sulfate inhibit phospholipase activity at pH 5.5 but have little effect on activity at pH 7.5. All detergents tested inhibited phospholipase activity, and both activities are inhibited by reaction products, free fatty acid and lysophosphatidylethanolamine. This product inhibition is only partially prevented by addition of albumin. Supernatant fractions of granulocyte homogenates contain a heat-labile inhibitor of granule phospholipase activity at pH 7.5. Boiling the fraction not only removes the inhibition but actually results in stimulation of hydrolysis at pH 7.5 as well as pH 5.5. These granule-associated phospholipase A activities of polymorphonuclear leukocytes differ in several of their properties from granule or lysosomal phospholipases of other phagocytic cells.

Animals↗