No abstract

Some chemical and metabolic characteristics of polymorphonuclear leukocytes and monocytes from peritoneal exudates of the guinea pig, and of alveolar macrophages from the same animal, have been compared. Changes in the metabolic patterns of these three types of cell have been followed during the act of phagocytosis. The effect of conventional inhibitors of metabolism, and of anaerobiosis on the phagocytic ability of each of the three cell types mentioned has also been determined. From these studies it was found that alveolar macrophages depend to a considerable degree upon oxidative phosphorylation to provide energy for phagocytosis. The other two types of cell depend only on glycolysis as the source of metabolic energy for that function. In some experiments aimed at obtaining information on the possible role of complex lipids in the function of the cell membrane, it was noted that phagocytosis stimulated the incorporation of inorganic phosphate-P 32 into the phosphatides of both types of cell from peritoneal exudates--whether these were free-swimming or adherent to a surface. This phenomenon has not yet been detected in the case of alveolar macrophages.During the past several years, a number of studies have been carried out on the metabolic concomitants of the phagocytic act in leukocytes. Almost all of these observations were made on polymorphonuclear leukocytes. Only a few data have been reported for monocytes (1-4). The object of the present experiments was to examine the metabolic basis of the phagocytic event in mononuclear cells and in alveolar macrophages and to compare these cells with polymorphonuclear leukocytes. This seemed to be of importance, because, although polymorphonuclear leukocytes are the most immediate phagocytizing cells during infection, they are very short-lived. The macrophages, of which the peritoneal mon0nuclear leukocytes and the alveolar macrophages may be representative, are of major importance as defenses against invading organisms. Alveolar macrophages are particularly intriguing cells and have recently been the subject of considerable morphological study (5). There has been a good deal of discussion of their origin (5-8) and function (6,8).This paper presents information on the chemical characteristics of these three types of phagocyte, all obtained from the guinea pig, as well as comparisons of the metabolic changes which accompany phagocytosis. Definite differences with respect to the source of metabolic energy for phagocytosis, between the alveolar macrophages on the one hand and the peritoneal exudate monocytes and polymorphonuclear leukocytes on the other, were found.

Human Mn superoxide dismutase (MnSOD) encoded by chromosome 6 is a mitochondrial matrix enzyme positioned to scavenge oxygen radicals produced by the extensive oxidation-reduction and electron transport reactions undergoing in that organelle. cDNA clones containing the entire coding region for human MnSOD were isolated from a T-lymphocyte cDNA library in A gt1O. The cDNA contains a 666 bp coding region followed by a 3' untranslated region which lacks the AATAAA polyadenylation signal. The predicted amino acid sequence is in accordance with the published amino acid sequence of human liver MnSOD (1) with the following exceptions: Glu instead of Gln at positions 42, 88 and 109 and an additional Gly-Trp after amino acids 123. The deduced protein sequence extends 24 amino acids upstream from the N-terminal Lys of human MnSOD, suggesting a pre-peptide. Hence human MnSOD is composed of 222 amino acids, 24 of which are removed during processing and maturation of the enzyme.

Viroporins are a family of small hydrophobic proteins found in many enveloped viruses that are capable of ion transport. Building upon the ability to inhibit influenza by blocking its archetypical M2 H+ channel, as a family, viroporins may represent a viable target to curb viral infectivity. To this end, using three bacterial assays we analyzed six small hydrophobic proteins from biomedically important viruses as potential viroporin candidates. Our results indicate that Eastern equine encephalitis virus 6k, West Nile virus MgM, Dengue virus 2k, Dengue virus P1, Variola virus gp170, and Variola virus gp151 proteins all exhibit channel activity in the bacterial assays, and as such may be considered viroporin candidates. It is clear that more studies, such as patch clamping, will be needed to characterize the ionic conductivities of these proteins. However, our approach presents a rapid procedure to analyze open reading frames in other viruses, yielding new viroporin candidates for future detailed investigation. Finally, if conductivity is proven vital to their cognate viruses, the bio-assays presented herein afford a simple approach to screen for new channel blockers.