Author
Seymour J. Klebanoff
Bio: Seymour J. Klebanoff is an academic researcher from United States Public Health Service. The author has contributed to research in topics: Lactoperoxidase & Uterus. The author has an hindex of 4, co-authored 4 publications receiving 1638 citations.
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TL;DR: Myeloperoxidase, at high concentrations, exerted an antibacterial effect on L. acidophilus in the absence of added halide, which also was temperature- and catalase-sensitive, and suggests that, under the conditions employed, the antibacterial properties of a weak acid extract of guinea pig leukocytes is due, in part, to its peroxid enzyme content, particularly if a halide is present in the reaction mixture.
Abstract: An antibacterial effect of myeloperoxidase, a halide, such as iodide, bromide, or chloride ion, and H2O2 on Escherichia coli or Lactobacillus acidophilus is described. When L. acidophilus was employed, the addition of H2O2 was not required; however, the protective effect of catalase suggested that, in this instance, H2O2 was generated by the organisms. The antibacterial effect was largely prevented by preheating the myeloperoxidase at 80 C or greater for 10 min or by the addition of a number of inhibitors; it was most active at the most acid pH employed (5.0). Lactoperoxidase was considerably less effective than was myeloperoxidase when chloride was the halide employed. Myeloperoxidase, at high concentrations, exerted an antibacterial effect on L. acidophilus in the absence of added halide, which also was temperature- and catalase-sensitive. Peroxidase was extracted from intact guinea pig leukocytes by weak acid, and the extract with peroxidase activity had antibacterial properties which were similar, in many respects, to those of the purified preparation of myeloperoxidase. Under appropriate conditions, the antibacterial effect was increased by halides and by H2O2 and was decreased by catalase, as well as by cyanide, azide, Tapazole, and thiosulfate. This suggests that, under the conditions employed, the antibacterial properties of a weak acid extract of guinea pig leukocytes is due, in part, to its peroxidase content, particularly if a halide is present in the reaction mixture. A heat-stable antibacterial agent or agents also appear to be present in the extract.
819 citations
TL;DR: Iodination of the bacteria by the myeloperoxidase-iodide-H2O2 system was demonstrated chemically and radioautographically and suggests the involvement of labile intermediates of iodide oxidation rather than the more stable end products of oxidation such as iodine.
Abstract: Myeloperoxidase, iodide, and H2O2 have a bactericidal effect on Escherichia coli. Myeloperoxidase can be replaced in this system by lactoperoxidase or by a guinea pig leukocyte particulate preparation, H2O2 by an H2O2-generating system such as glucose and glucose oxidase, and iodide by thyroxine or triiodothyronine. The bactericidal effect was high at pH 5.0 and fell as the pH was increased. Preincubation of myeloperoxidase, iodide, and H2O2 for 30 min before the addition of the bacteria largely prevented the bactericidal effect. Thus, the organisms must be present in the reaction mixture during iodide oxidation for maximum killing, which suggests the involvement of labile intermediates of iodide oxidation rather than the more stable end products of oxidation such as iodine. Iodination of the bacteria by the myeloperoxidase-iodide-H2O2 system was demonstrated chemically and radioautographically. Iodination and the bactericidal effect were similarly affected by changes in experimental conditions in all the parameters tested (effect of preincubation, pH, and inhibitors). Phagocytosis of bacteria by guinea pig leukocytes was associated with the conversion of iodide to a trichloroacetic acid-precipitable form. Iodide was localized radioautographically in the cytoplasm of human leukocytes which contained ingested bacteria. Iodide fixation was not observed in the absence of phagocytosis or in the presence of Tapazole.
609 citations
TL;DR: Observations correlate with previous biochemical studies by other workers, in which estrogens have been shown to promote the synthesis of uterine RNA, collagen, and noncollagenous protein, and suggest that smooth muscle cells may participate inThe synthesis of connective tissue proteins.
Abstract: The fine structure of the estrogen-primed uterus was examined in two series of rats, with emphasis upon the alterations in smooth muscle cells and fibroblasts. The first series of animals were mature animals that were sacrificed at diestrus or estrus. The second series consisted of prepubertal rats (57-70 g) that received subcutaneous injections of estradiol-17 beta in 20% alcohol. Four groups of animals received the hormone twice daily for 3 days for a total dose of 0.06, 0.6, 6.0, or 60.0 microg, respectively. An estrogenic response was observed in all groups as indicated by an increase in uterine weight. Control groups consisted of either untreated animals or animals receiving 20% alcohol. All animals were sacrificed on the 4th day. The fibroblasts and smooth muscle cells in the controls were similar to their counterparts in the mature animal in diestrus. They were small, contained relatively little rough endoplasmic reticulum, and the connective tissue cells appeared like fibrocytes. All of the estrogen-treated animals were similar in appearance and were comparable to their counterparts in the mature animal in estrus. Both the smooth muscle cells and the fibroblasts were increased in size, demonstrated a marked enlargement and dilation of ergastoplasmic cisternae, and contained increased numbers of attached and free cytoplasmic ribosomes. The presence of an extensive rough endoplasmic reticulum in the smooth muscle cells of the stimulated uterus is in marked contrast to the appearance of these cells in other tissues. These observations correlate with previous biochemical studies by other workers, in which estrogens have been shown to promote the synthesis of uterine RNA, collagen, and noncollagenous protein, and suggest that smooth muscle cells may participate in the synthesis of connective tissue proteins.
136 citations
TL;DR: The possible relationship of the turnover of eosinophils to the profound morphologic and chemical changes in the uterus during the estrous cycle was discussed.
Abstract: This study has presented the fine structure changes in the eosinophilic leukocyte in the rat uterus during the estrous cycle. Eosinophils were seen to emigrate into the uterine connective tissues from the blood stream. Just prior to, during estrus, and 1 day postestrus, eosinophilic leukocytes underwent lysis releasing their contents into the extracellular spaces and both whole eosinophils and individual granules from lysed cells were ingested by resident macrophages. No phagocytic activity by eosinophils was observed. The possible relationship of the turnover of eosinophils to the profound morphologic and chemical changes in the uterus during the estrous cycle was discussed.
107 citations
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TL;DR: O(2) (-) is made by leukocytes under circumstances which suggest that it may be involved in bacterial killing, and is identified as the agent responsible for the leukocyte-mediated reduction of cytochrome c.
Abstract: As a highly reactive substance produced in biological systems by the one-electron reduction of oxygen, superoxide (O(2) (-)) seemed a likely candidate as a bactericidal agent in leukocytes. The reduction of cytochrome c, a process in which O(2) (-) may serve as an electron donor, was found to occur when the cytochrome was incubated with leukocytes. O(2) (-) was identified as the agent responsible for the leukocyte-mediated reduction of cytochrome c by the demonstration that the reaction was abolished by superoxide dismutase, an enzyme that destroys O(2) (-), but not by boiled dismutase, albumin, or catalase. Leukocyte O(2) (-) production doubled in the presence of latex particles. The average rate of formation of O(2) (-) in the presence of these particles was 1.03 nmol/10(7) cells per 15 min. This rate, however, is only a lower limit of the true rate of O(2) (-) production, since any O(2) (-) which reacted with constituents other than cytochrome c would have gone undetected. Thus. O(2) (-) is made by leukocytes under circumstances which suggest that it may be involved in bacterial killing.
2,887 citations
TL;DR: Since Metschnikoff's discovery, hundreds of scientists studying dozens of species have reported thousands of studies on these cells, perhaps the most widely recognized of which are those of the eminent English scientists.
Abstract: (First of Two Parts) THE part played by phagocytes in defense against invading pathogens has been recognized since 1883. In that year, Metschnikoff, a Russian zoologist, reported that foreign particles injected into metazoans (in Metschnikoff's experiments, starfish larvae) were taken up by a population of "wandering mesodermal cells" that resided in interstitial tissues.1 He postulated a crucial role in host defense for these wandering cells, which he named "phagocytes." Since Metschnikoff's discovery, hundreds of scientists studying dozens of species have reported thousands of studies on these cells, perhaps the most widely recognized of which are those of the eminent English . . .
2,457 citations
TL;DR: It is concluded that the MPO system plays an important role in the microbicidal activity of phagocytes and the role of theMPO system in tissue injury.
Abstract: Neutrophilic polymorphonuclear leukocytes (neutrophils) are highly specialized for their primary function, the phagocytosis and destruction of microorganisms. When coated with opsonins (generally complement and/or antibody), microorganisms bind to specific receptors on the surface of the phagocyte and invagination of the cell membrane occurs with the incorporation of the microorganism into an intracellular phagosome. There follows a burst of oxygen consumption, and much, if not all, of the extra oxygen consumed is converted to highly reactive oxygen species. In addition, the cytoplasmic granules discharge their contents into the phagosome, and death of the ingested microorganism soon follows. Among the antimicrobial systems formed in the phagosome is one consisting of myeloperoxidase (MPO), released into the phagosome during the degranulation process, hydrogen peroxide (H2O2), formed by the respiratory burst and a halide, particularly chloride. The initial product of the MPO-H2O2-chloride system is hypochlorous acid, and subsequent formation of chlorine, chloramines, hydroxyl radicals, singlet oxygen, and ozone has been proposed. These same toxic agents can be released to the outside of the cell, where they may attack normal tissue and thus contribute to the pathogenesis of disease. This review will consider the potential sources of H2O2 for the MPO-H2O2-halide system; the toxic products of the MPO system; the evidence for MPO involvement in the microbicidal activity of neutrophils; the involvement of MPO-independent antimicrobial systems; and the role of the MPO system in tissue injury. It is concluded that the MPO system plays an important role in the microbicidal activity of phagocytes.
2,070 citations
TL;DR: Killing was previously believed to be accomplished by oxygen free radicals and other reactive oxygen species generated by the NADPH oxidase, and by oxidized halides produced by myeloperoxidase, but this is incorrect.
Abstract: Neutrophils provide the first line of defense of the innate immune system by phagocytosing, killing, and digesting bacteria and fungi. Killing was previously believed to be accomplished by oxygen free radicals and other reactive oxygen species generated by the NADPH oxidase, and by oxidized halides produced by myeloperoxidase. We now know this is incorrect. The oxidase pumps electrons into the phagocytic vacuole, thereby inducing a charge across the membrane that must be compensated. The movement of compensating ions produces conditions in the vacuole conducive to microbial killing and digestion by enzymes released into the vacuole from the cytoplasmic granules.
1,672 citations
TL;DR: Investigations of the morphology of smooth muscle derived from the inner media and intima of immature guinea pig aorta and radioautographic observations of the ability of aortic smooth muscle to synthesize and secrete extracellular proteins demonstrate that this cell is a connective tissue synthetic cell.
Abstract: Smooth muscle derived from the inner media and intima of immature guinea pig aorta were grown for up to 8 wk in cell culture. The cells maintained the morphology of smooth muscle at all phases of their growth in culture. After growing to confluency, they grew in multiple overlapping layers. By 4 wk in culture, microfibrils (110 A) appeared within the spaces between the layers of cells. Basement membrane-like material also appeared adjacent to the cells. Analysis of the microfibrils showed that they have an amino acid composition similar to that of the microfibrillar protein of the intact elastic fiber. These investigations coupled with the radioautographic observations of the ability of aortic smooth muscle to synthesize and secrete extracellular proteins demonstrate that this cell is a connective tissue synthetic cell.
1,584 citations