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At least 19 recordsLinked to original sources
PubMed1979

Cytochemical analysis of organelle degradation in phagosomes and apoptotic cells of the mucoid epithelium of mice.

The activity of mitochondrial cytochrome oxidase and peroxisomal catalase in the phagolysosomes and apoptotic bodies of mucoid epithelial cells was analysed. Tissue from 2-6 day old mice was used. The activity of acid phosphatase in lysosomes was also estimated. Cytochrome oxidase was demonstrated in well-preserved mitochondria inside phagosomes. Mitochondria in cells exhibiting apoptotic death also show activity of cytochrome oxidase. The enzyme activity in swollen mitochondria ceases before the membranes of the cristae disappear completely. Apoptotic bodies are phagocytosed by sister mucoid cells and, later on, they are digested inside the cell. Phagosomes which contain already degraded mitochondria show still active catalase in sequestered peroxisomes. The acid phosphatase involved in degradation of phagocytosed material originates from endocytosed lysosomes and primary and secondary lysosomes which fuse with the membranes of phagosomes.

Acid Phosphatase↗
PubMed1979

Inhibition of the discharge of endocytosed protein from phagosomes into lysosomes in hepatoma cells exposed to dimerized ribonuclease A.

The mechanism of the cytostatic action of dimerized ribonuclease A toward cultured hepatoma cells was investigated. A decrease in mitotic index, modifications of adsorptive properties of the pericellular membrane and inhibition of the degradation of two different proteins taken up by endocytosis are the first cell functions to be affected by the dimer. This effect on protein digestion is not due to an inhibition of proteolytic enzymes. The intracellular localization of exogenous protein and of ribonuclease dimer was studied by cell fractionation. When proteins (horseradish peroxidase or rabbit immunoglobulin G) are taken up by control hepatoma cells, they are first associated with phagosomes equilibrating at a lower density than lysosomes; their density distribution gradually becomes similar to that of lysosomes. When cells are pre-exposed to ribonuclease dimer, this modification of the density distribution as a function of time no longer occurs, although these proteins are still intracellular, as indicated by fractionation by differential centrifugation. During the first hour after addition of ribonuclease dimer, kinetic studies show an increased fixation of peroxidase to the cell membrane. Protein release into the culture medium is also increased. These results can be explained either by an absence of fusion between phagosomes and lysosomes, or by an inhibition of the discharge of peroxidase adsorbed to the phagosomal membrane after fusion.

Animals↗
PubMed1977

Effects of colchicine on phagosome-lysosome interaction in retinal pigment epithelium. II. In vitro observations on histio-organotypical retinal pigment epithelial cells of the pig (a preliminary report).

Phagocytic activity of histiotypical and organotypical retinal pigment epithelial cells was studied by SEM and EM. After a latent period polystyrene microspheres of different diameter were captured by newly formed microvilli. No mechanism of discrimination according to the size of microspheres was observed. After engulfment, microvilli of histiotypical cells decreased in length and finally disappeared. Lysosomes increased in number when compared to unstimulated cells and fused with many latex-containing phagosomes. Colchicine, when added at 5 X 10(-5) M to the medium, inhibits phagosome-lysome interaction, thus confirming in vivo observations.

Animals↗
PubMed1979

Effects of anionic inhibitors of phagosome-lysosome fusion in cultured macrophages when the ingested organism is Mycobacterium lepraemurium.

The mouse pathogen Mycobacterium lepraemurium is readily phagocytosed by cultured mouse peritoneal macrophages. Ingestion is normally followed by fusion between phagosomes and lysosomes. The influence of some aninonic compounds known to inhibit fusion in other systems was investigated by transmission electron microscopy after ingestion of M. lepraemurium. Fusion was markedly, although temporarily, inhibited by suramin and moderately inhibited by poly-D-glutamic acid. The effects are, however, not sufficient to permit these agents to be used to study the long-term effects of shutting off the secondary lysosome-phagosome fusion system in cultured macrophages infected with M. lepraemurium.

Animals↗
PubMed1977

Effects of colchicine on phagosome-lysosome interaction in retinal pigment epithelium. I. In vivo observations in albino rats.

The retinal pigment epithelium (RPE) from young albino rats was examined under light and electron microscope 2 1/2 to 16 h after intravenous injections of colchicine (0.5 mg per 100 gm body weight). One of the primary effects of colchicine treatment on the RPE is the appearance of extensive acPase-positive dense body aggregates in the Golgi area. The size of the aggregates and the disappearance of microtubules appear to be related to the length of time allowed for colchicine to react. Acid phosphatase (acPase) activity is localized on the dense body aggregates and is particularly evident at a light microscopic level, where it can be observed as darkly stained clumps. Dense bodies are only rarely seen in the immediate proximity of acPase-positive phagosomes in colchicine-treated animals. The results of these experiments suggest the existence of an intracellular transport mechanism for acPase-carrying dense bodies. This intracellular transport is inhibited by colchicine, being probably related to a block of microtubular assembly.

Animals↗
PubMed1979

Phagosome-lysosome fusion and cyclic adenosine 3':5'-monophosphate in macrophages infected with Mycobacterium microti, Mycobacterium bovis BCG or Mycobacterium lepraemurium.

When ingested by mouse peritoneal macrophage monolayers, live Mycobacterium microti caused a sustained increase in monolayer cyclic AMP content and fusion of lysosomes with the bacterium-containing phagosomes was impaired. Ingested live M. bovis BCG caused a transient increase in cyclic AMP and the defect in phagolysosome formation was less pronounced. Dead mycobacteria and live M. lepraemurium neither enhanced monolayer cyclic AMP content nor inhibited phagolysosome formation. Mycobacterium microti and BCG exceeded M. lepraemurium in cyclic AMP-synthesizing activity in vitro but the question of whether bacterial cyclic AMP contributed substantially to the increments in infected macrophages was not resolved. Antibody-coated BCG retained the ability to synthesize cyclic AMP and to enhance monolayer cyclic AMP but lost the ability to inhibit phagolysosome formation in macrophages, The observations are discussed in terms of possible control of phagolysosome formation by cyclic nucleotides.

Cyclic AMP↗
PubMed1978

Gonococcal interactions with polymorphonuclear neutrophils: importance of the phagosome for bactericidal activity.

Gonococci are capable of attaching to the surface of polymorphonuclear leukocytes (PMN). In this location they resist phagocytosis and are not killed by PMN. To delineate the factors involved in the survival of these gonococci, we investigated the interaction of virulent gonococci, which adhere to cells and resist phagocytosis, and avirulent gonococci, which are phagocytized and killed by PMN. In the presence of serum, both virulent and avirulent gonococci associate equally well with PMN and stimulate increases in oxidative metabolism. In the absence of serum virulent gonococci attached to PMN and stimulated PMN oxidative metabolism to a greater extent than avirulent gonococci which did not attach to PMN (P = 0.0009). Therefore, the survival of virulent gonococci attached to the PMN surface is not a result of failure to activate oxidative and bactericidal mechanisms. Both virulent and avirulent gonococci stimulated equivalent PMN specific granule release as measured by the appearance of lactoferrin in the media. Phagocytosis of avirulent gonococci stimulated significantly greater beta-glucuronidase release (P = 0.01) and myeloperoxidase-mediated iodination of protein (P = 0.001) by PMN than attachment of virulent gonococci. In the absence of serum neither type of gonococci stimulated beta-glocuronidase release or protein iodination by PMN. Thus, virulent gonococci fail to stimulate primary granule release by PMN. To further assess the role of attachment versus ingestion on the survival of gonococci, PMN were treated with cytochalasin B to block ingestion. Cytochalasin B-treated PMN were unable to kill either virulent or avirulent gonococci despite normal degranulation stimulated by the latter. The failure of PMN to kill surface-attached gonococci appears to be a consequence of the failure of PMN to enclose the virulent gonococci within a phagosome. The phagocytic vacuole thus plays a critical role in normal PMN bactericidal activity by providing a closed space in which the proper concentration of substances may be achieved to generate microbicidal activity.

Blood Bactericidal Activity↗
PubMed1976

Phagocytosis in human platelets: localization of acid phosphatase-positive phagosomes following latex uptake.

Incubation of human platelets in plasma containing a suspension of latex particles for 1-90 min resulted in progressive accumulation of particles in the open-channel system, followed by localization of latex in electron-opaque vacuoles. After 60 min, acid phosphatase was localized within latex-containing vacuoles. The periodate-alkaline-bismuth reaction intensely stained external membranes and membranes of the open-channel system. Membranes of latex-containing organelles were not stained. Latex phagocytosis was independent of both anticoagulant choice and aspirin effects. Our results indicate that the platelet can act as a true phagocyte, and we suggest that the phagocytic process is chronologically similar to that reported for polymorphonuclear leukocytes.

Acid Phosphatase↗
PubMed1977

Turnover of rod photoreceptor outer segments. I. Membrane addition and loss in relationship to temperature.

Membrane turnover in outer segments of Rana pipiens red rods (ROS) was studied in tadpoles maintained under cyclic lighting (12L:12D) at 23 degrees, 28 degrees, and 33 degrees C. Large fragments (greater than 2 microns in diameter or length) were shed from the ROS tips shortly after the onset of light. These were phagocytized by the pigment epithelium (PE) which caused an increase in the number of phagosomes greater than 2 microns in size (large phagosomes). Large phagosomes were present in highest numbers 2-4 h after light exposure and were degraded by 8-12 h. The proportion of ROS that shed each day after the onset of the light cycle increased with increment increases in temperatures (23 degrees C-18%, 28 degrees C-33%, 33 degrees C-42% per day), resulting, in a reduction in the average interval of time between repeated sheddings (23 degrees C-5.6 days, 28 degrees C-3 days, 33 degrees C-2.4 days) though the average numbers of disks shed from ROS at the various temperatures were not significantly different (23 degrees C-139.5 +/- 5.7, 28 degrees C-129.4 +/- 7.6, 33 degrees C-129.9 +/- 4.8 disks/shed packet). Phagosomes in the PE that were less than 2 microns in diameter (small phagosomes) were present in relatively constant numbers throughout the day, and their numbers increased at higher temperatures. The absence of a concomitant increase in small phagosomes as large phagosomes were degraded indicates that large phagosomes were not the major source of small phagosomes. When the PE was isolated to culture in the absence of the retina, these small phagosomes were degraded. The rate of disk addition to the ROS base was determined by autoradiography after [3H]leucine injection. The number of disks added per day increased with elevations of temperature (23 degrees C-32.4; 28 degrees C-55.9; 33 degrees C-65.5). The average number of disks added to the ROS between repeated sheddings (23 degrees C-181.4; 28 degrees C-167.7; 33 degrees C-157.2) was greater than the number of disks shed after light exposure. Inasmuch as the ROS show no net increase in length during the tadpole stages utilized, the remaining disks must be lost at some other time. Electron microscope analysis revealed the presence of small groups of disks in curled configurations at the tips of ROS, suggesting possible stages of detachment.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1979

Intracellular localization of Rickettsia tsutsugamushi in polymorphonuclear leukocytes.

Rickettsia tsutsugamushi (Gilliam strain) was serially propagated in BHK-21 cell cultures and incubated with guinea pig peritoneal polymorphonuclear leukocytes to study the ultrastructural features of rickettsial uptake and entry into the leukocytes. Significant numbers of rickettsiae were phagocytized selectively by these leukocytes within 30 min. About one-half of these rickettsiae remained sequestered in phagosomes but the other one-half were free from the phagosome and localized directly in the polymorphonuclear leukocyte cytoplasm. Various stages of rickettsial release from the phagosomes were observed. Once free within the polymorphonuclear leukocyte cytoplasm, the rickettsiae were preferentially localized in the glycogen-packed areas which are devoid of lysosomes and other cytoplasmic organelles. This study indicates that rickettsiae phagocytized by polymorphonuclear leukocytes can escape from the phagosome into the cytoplasm.

Animals↗