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Biomedical subjects

H L Bank

Publications and source records attributed to H L Bank.

46 records · Page 3Linked to original sources
PubMed1978

Phagocytosis of bacteria by polymorphonuclear leukocytes. A freeze-fracture, scanning electron microscope, and thin-section investigation of membrane structure.

The changes in membrane structure of rabbit polymorphonuclear (PMN) leukocytes during bacterial phagocytosis was investigated with scanning electron microscope (SEM), thin-section, and freeze-fracture techniques. SEM observations of bacterial attachment sites showed the involvement of limited areas of PMN membrane surface (0.01-0.25mum(2)). Frequently, these areas of attachment were located on membrane extensions. The membrane extensions were present before, during, and after the engulfment of bacteria, but were diminished in size after bacterial engulfment. In general, the results obtained with SEM and thin-section techniques aided in the interpretation of the three-dimensional freeze-fracture replicas. Freeze-fracture results revealed the PMN leukocytes had two fracture faces as determined by the relative density of intramembranous particles (IMP). Membranous extensions of the plasma membrane, lysosomes, and phagocytic vacuoles contained IMP's with a distribution and density similar to those of the plasma membrane. During phagocytosis, IMPs within the plasma membrane did not undergo a massive aggregation. In fact, structural changes within the membranes were infrequent and localized to regions such as the attachment sites of bacteria, the fusion sites on the plasma membrane, and small scale changes in the phagocytic vacuole membrane during membrane fusion. During the formation of the phagocytic vacuole, the IMPs of the plasma membrane appeared to move in with the lipid bilayer while maintaining a distribution and density of IMPs similar to those of the plasma membranes. Occasionally, IMPs were aligned to linear arrays within phagocytic vacuole membranes. This alignment might be due to an interaction with linearly arranged motile structures on the side of the phagocytic vacuole membranes. IMP-free regions were observed after fusion of lysosomes with the phagocytic vacuoles or plasma membrane. These IMP-free areas probably represent sites where membrane fusion occurred between lysosomal membrane and phagocytic vacuole membrane or plasma membrane. Highly symmetrical patterns of IMPs were not observed during lysosomal membrane fusion.

Animals↗
PubMed1978

Intramembranous particles in erythrocyte, reticulocyte and erythroblastic leukemic cells of the rat: a model system for erythrocyte maturation.

The density and size distribution of intramembranous particles (IMP) were determined for cells of the erythroid series. The number and size of IMP were measured on both fracture faces of erythroblastic leukemia cells, phenylhydrazine-induced reticulocytes and mature erythrocytes. We found that the number of IMP adhering to the protoplasmic fracture face of the plasma membrane increased with increasing maturation, while the number of particles adhering to the external fracture face did not correlate with maturational stage. In general, the mean size of particles adhering to both fracture faces decreased with increasing maturation after the erythroblastic stage. We interpret these results to mean that the IMP seen are derived from more than one macromolecular species and that they are distributed asymmetrically in the plasma membrane.

Animals↗
PubMed1978

Human marrow erythropoiesis in culture: III. Ultrastructural and cytochemical studies of cellular interactions.

Human erythroblasts cultured with a methylcellulose clonal assay technique were studied with ultrastructural and cytochemical methods. The intact colonies contained only erythroblasts at a similar stage of maturation, and no macrophages were identified within the colonies. The cultured erythroblasts demonstrated many of the morphologic features described in vivo. Neutral and acid glycoconjugates identified on the plasmalemma stained in a similar way to that seen in vivo with a concanavalin A horseradish peroxidase bridge and dialyzed iron technique. Weak acid phosphatase activity and ferritin-like particles were demonstrated in siderosomes, but these structures lacked peroxidase activity and dialyzed iron reactive acid mucosubstance. Transmission and scanning electron microscopy identified numerous processes which connected early erythroblasts and resembled those described in the marrow of patients with dyserythropoietic disorders. These findings suggest the presence of abnormalities in cultured erythrocytes which should be considered when evaluating pathologic specimens in vitro.

Bone Marrow Cells↗
PubMed1977

Granule release by polymorphonuclear leukocytes treated with the ionophore A23187.

Polymorphonuclear leukocytes (PMN's) incubate three to eight minutes at 37 degrees C in medium containing 1 X 10(-6) M of the ionophore antibiotic A23187 released their cytoplasmic granules into the extracellular medium. Transmission electron microscopy of treated cells showed microfilament bundles extending between adjacent granules within the cytoplasm and between granules and the plasma membrane. Tiny dense projections (beads) 8-12 nm in diameter were observed along segments of the cytoplasmic surface of the plasma membrane with a periodicity of 20-30 nm. These beads were observed on the plasma membrane only in the vicinity of intra- or extracytoplasmic granules. The structural relationships of the beads with the plasma membrane microfilaments suggest they play a role in the process of ionophore-induced granule release from polymorphonuclear leukocytes.

Animals↗
PubMed1976

Association of microfilament bundles with lysosomes in polymorphonuclear leukocytes.

The juxtaposition of microfilament bundles and lysosomes seen both in thin-sectioned cells in the transmission electron microscope and in cryofractured cells in the scanning electron microscope, and the presence of short filamentous structures between lysosomes and microfilament bundles, suggest that microfilaments may be attached to lysosomal membranes and that these filaments may be involved in lysosomal movements. Further work is in progress to test these hypotheses.

Animals↗
PubMed1976

Human marrow erythropoiesis in culture. I. Characterization of methylcellulose colony assay.

We examined the morphological and functional characteristics of human marrow erythrocytes cultured with a recently developed methylcellulose colony assay technique. Erythrocytic cells in various stages of development were observed, and a significant degree of maturational synchrony within individual colonies was noted. By light microscopy, colonies consisting of late normoblasts appeared compact, had an orange hue attributable to their hemoglobin, and demonstrated pseudoperoxidase activity, whereas colonies composed of early erythroblasts grew less compact or in clusters of smaller cell aggregates and showed no reddish tinge. Colonies possessing intermediate features were also observed. Maturational synchrony of individual colonies was confirmed using ransmission and scanning electron microscopy. The ultrastructure and cytochemistry of most immature cells were normal. The mature erythrocytes, however, were severely microcytic and hypochromic and contained one to several Heinz bodies. These defects in the cytoplasmic maturation of erythrocytes corresponded with impaired granulocytic maturation in culture, which we observed previously, and suggest environmental or nutritional defects in culture. Linearity of the method was confirmed using five normal bone marrows. Erythropoietin dose-responses observed in ten normal marrows were comparable to the previously reported results and revealed significant variation in individual plating efficiencies.

Adult↗
PubMed1975

Scanning electron microscopy of copper-containing intrauterine devices: long-term changes in utero.

The addition of metallic copper wire to a polyethylene intrauterine device dramatically increases the efficacy of that device. A series of copper-containing Tatum-T devices which had been carried in utero for 2 to 3 years was examined by scanning electron microscopy. Few of these devices showed evidence of corrosion or pitting of the copper, as had been reported previously. Almost all of the Ts showed a definite pattern of layering of fibrinoid deposits; intact cells, cellular debris, and crystalline structures were also seen. The micrographs show an extensive buildup of surface layers which, we believe, encase the copper in a semipermeable matrix. This matrix may retard the diffusion of copper compounds into the uterus sufficiently to compromise the contraceptive action of the copper.

Copper↗
PubMedDate not supplied

Videoanalysis of chemokinesis: characterization of speed, persistence and orientation in an agarose assay.

Time-lapse video recording and off-line computer analysis were used to characterize the chemokinetic behavior of individual human neutrophils migrating in an agarose assay. When neutrophils were stimulated with an isotropic concentration of formyl-methionyl-leucyl-phenylalanine (fMLP), they migrated with a mean speed of 9.6 micron per min and oriented at random. The ratio of net displacement to total distance travelled (persistence of locomotion) was 0.66, indicating that neutrophils maintained some directional persistence even in the absence of a gradient of fMLP. The speed and persistence of locomotion index were correlated because both faster and slower cells had high persistence, while only slower cells had low persistence. The orientation angle was independent of both speed and persistence of locomotion. These are the first reported direct measurements of the chemokinetic locomotion of neutrophils using the agarose assay.

Chemotaxis, Leukocyte↗
PubMedDate not supplied

Kinematic analysis of chemotaxis of fresh and stored neutrophils.

When neutrophils are isolated from the circulation the first function to begin to deteriorate is chemotaxis. To characterize the loss of chemotaxis that occurs during storage, a computer-assisted video motion analysis of neutrophils responding to formyl-methionyl-leucyl-phenylalanine (FMLP) was used in an agarose assay. The chemotactic speed, velocity, and orientation angle were measured, and a persistence of locomotion index (velocity/speed) and chemotropic index (cosine of the orientation angle) were calculated for fresh neutrophils and neutrophils stored in plasma at 20 to 22 degrees C for 24 hours. The data reveal that: (1) the frequency distribution of speed for individual stored cells had a different shape than that of fresh cells owing to a subpopulation of stored cells (approximately 35 percent) which migrated at a slower mean speed; (2) the frequency distribution of orientation for fresh cells is not normally distributed and contains a subpopulation (approximately nine percent of the total) of cells which orient at random in a gradient; (3) the precision of orientation of the majority of stored cells is comparable to that of fresh cells, but approximately 35 percent of the stored cells orient at random in a chemoattractant gradient; (4) neither the persistence index nor the orientation of both fresh and stored cells were correlated with speed; (5) the chemotropic index and persistence index are correlated, and this correlation is not altered by storage suggesting that stored cells which show decreased persistence also show a decreased chemotropic index. It is proposed that neutrophils respond to a gradient of fMLP with either fast, persistent, accurately oriented locomotion or slower, less persistent, randomly oriented locomotion. In addition to those neutrophils which do not migrate in response to fMLP, it is proposed that there are two subpopulations of motile neutrophils. Storage at 20 to 22 degrees C induces shifts between these three modes of behavior.

Blood Preservation↗