Yasuo Ichikawa

Control of macrophage and granulocyte colony formation by two different factors

Abstract A conditioned medium from a culture of mouse peritoneum showed high activity in stimulating colony formation by mouse bone marrow cells in vitro. In the conditioned medium, two types of activities were separated. The larger molecular component (M fraction) was trypsin-resistant and stimulated macrophage colony formation, and the smaller component (G fraction) was trypsin-sensitive and stimulated granulocyte colony formation. An increased concentration of the G fraction always brought about an increase in granulocyte colonies accompanied by a marked decrease in the number of macrophage colonies. The presence of an inhibitor for macrophage growth is also discussed.

Torsional flutter of bluff bodies

This paper describes the torsional flutter mechanism of 2D rectangular cylinders and 2D H-shaped cylinders based upon unsteady pressure measurements under forced torsional vibration. For some cylinders with certain side ratio (BD, B: chord length, D: cylinder thickness), such as BD = 5 to BD = 12.5, in the high reduced velocity range, that is V/f B> 10 (f: torsional frequency, V: approaching flow velocity), the torsional flutter mechanism is fundamentally identical with that of coupled flutter, however, in the low reduced velocity range, that is roughly V/f B # 8, the torsional flutter would be induced by vortex convection along side-surface of the cylinder, which is evidently different from that of coupled flutter. Furthermore, for bluffer cylinders such as 2D rectangular cylinders with BD = 2 and 2D H-shaped cylinder with BD = 3, torsional flutter shows a particular characteristic of velocity-restricted type, but not divergent type in smooth flow. This flutter is mainly controlled by the phase difference between separated flow from the leading edge and torsional response, which gradually changes with flow velocity, where vortex convection seems to play a less important role in the excitation.

Interaction of lymphocytes and macrophage cell line cells (M1 cells): I. Functional maturation and appearance of Fc receptors in M1 cells

Abstract M 1 cells, which are cell line cells established from myeloid leukemia cells of the SL strain mouse, can differentiate from blast cells ( M 1 − ) to mature macrophages ( M 1 + ) within 48 hr, when they are cultured with conditioned medium (CM) obtained from murine embryonic fibroblasts. While M 1 − cells have no phagocytic activity nor Fc receptor (FcR), M 1 + cells possess both characteristics. The appearance of FcR is temperature-dependent and inhibited by a metabolic inhibitor, cycloheximide. FcR on M 1 + cells is resistant to trypsin and pronase. M 1 + cells improve the viability of macrophage-depleted SL splenic lymphocytes and restore the in vitro secondary plaque forming cell response of macrophage-depleted spleen cells to particulate and soluble antigens. M 1 − cells lack this macrophage-substituting capacity. Mm 1 cells, mutant cells from M 1 cells, having FcR and higher phagocytic activity than M 1 + cells, are also devoid of this capacity.

Changes in ultrastructures and enzyme activities during differentiation of myeloid leukemia cells to normal macrophages

Abstract Changes in ultrastructures and in enzyme activities were investigated electron microscopically, cytochemically and biochemically when mouse myeloid leukemia cells, Ml cell line, successfully differentiated to normal macrophages after incubation with a conditioned medium harvested from secondary embryo fibroblasts, or a lipopolysaccharide from Salmonella typhosa . The number of mitochondria increased significantly accompanied by the enhanced activity of cytochrome oxidase per cell, although the activity in each mitochondrion remained unchanged. The rough-surfaced endoplasmic reticulum elongated and often exhibited a concentrically multilayered lamellae. Glucose-6-phosphatase activity, a marker enzyme for the endoplasmic reticulum, also increased. Primary lysosomes were newly formed where acid phosphatase activity was positively demonstrated. Ten-nm cytoplasmic microfilaments, mainly forming bundles, and other microfilaments less than 6 nm wide were formed newly and abundant. Budding of type C viruses from the plasma membranes was reduced strikingly. Another established cell line, Mm-1, which spontaneously differentiated from the Ml cell line, was characterized completely by a macrophage, in which azurophilic granules (primary lysosomes), secondary lysosomes possessing strong activity of acid phosphatase and 10-nm microfilaments were most remarkable. These non-transplantable Mm-1 cells sometimes exhibited budding of viruses.

Induction of differentiated functions which are reversibly suppressed by cytochalasin B.

Abstract Induction of two differentiated functions, phagocytosis and locomotive activity, was confirmed to lead to cessation of cell growth in a myeloid leukemia cell line. This induction did not appear to require any preceding mitosis. Cytochalasin B-sensitive cell components were also produced in the cell line as a result of contact with a trypsin-sensitive factor present in the conditioned medium.

“Determination” of differentiation of bipotent hemopoietic progenitor cells in vitro☆

Abstract Murine bone marrow cells fractionated in a discontinuous density gradient of Ficoll-Metrizoate solution produced a fraction with more than 90% colony-forming efficiency. When this fraction was seeded in untreated CM from the abdominal wall, it produced neutrophil (66%), macrophage (25%), mixed type (7%) and blast cell (2%) colonies. When CM was used after trypsinization to inactivate the granulocyte stimulating activity, most of colonies found (93%) were macrophage which kept the number of colonies unchanged. Thus, we concluded that about 40% of the cells in the fraction were able to differentiate to both macrophages or neutrophils and that the direction of differentiation was controlled by humoral factors present in the culture medium.

Aerodynamic effects of the angle of attack on a rectangular prism

Abstract In the past, in-line vibration caused by low-velocity flows proved to be potentially very destructive. Therefore, in this paper, an experimental investigation concerning the aerodynamic properties of a 2×1 rectangular cross-sectional prism is presented. The 2×1 cross section was chosen specifically for the in-line vibration demonstrated by this shape in past studies. Through the use of wind tunnel tests, the aerodynamic response to various angles of attack were examined. Specifically, Strouhal numbers and vibrational response were measured at a number of different angles of attack for both two- and three-dimensional models. In addition, static aerodynamic force components and vortex formation around the prism were investigated for angles of 0° and 90°.

Induction and function of 2′,5′-oligoadenylate synthetase in differentiation of mouse myeloid leukemia cells

Abstract The activity of 2′,5′-oligoadenylate synthetase (2-5A synthetase), known to be induced by interferon, was detected in mouse myeloid leukemic M1 cells only when they differentiated to phagocytic cells after incubation with conditioned medium (CM) from rat embryo cells. However, no interferon activity occurred in culture fluids of CM-treated M1 cells, although some activity was detected in the cell extracts. When anti-interferon serum was added to M1 cell cultures, the induction of 2-5A synthetase by CM was suppressed. These results suggest that CM stimulated the M1 cells to produce a minute amount of interferon, which was reponsible for induction of the 2-5A synthetase activity. On the other hand, development of the phagocytic activity of M1 cells could not be influenced by addition of antiserum. Interferon added exogenously per se neither induced phagocytic activity of M1 cells, nor did it enhance the CM-induced differentiation of the cells. Moreover, dexamethasone, which induced differentiation of M1 cells, was not capable of inducing 2-5A synthetase. These results indicate that interferon and/or 2-5A synthetase plays no essential part in the differentiation of M1 cells.

Changes in Actin during Cell Differentiation

Since the pioneering work by Loewy and Hoffman-Berling, the actomyosin system has been believed to have an important function not only in muscle cells but in nonmuscle cells (reviewed by Pollard and Weihing, 1974). Non-muscle cell actin was first purified from Physarum by Hatano and Oosawa (1966a,b). Success in identifying actin filaments as arrowhead figures in situ (Ishikawa et al., 1969), methods devised to purify nonmuscle cell actin (Gordon et al., 1976a), and the establishment of a DNase I inhibition assay that measures actin contents (Blikstad et al., 1978) show the great progress made in this field. In addition, there has been increased interest in various nonmuscle cell actins, functional and chemical differences among actin molecules from different sources, as well as differences in their control mechanisms.

Plasma membranes purified from myeloid leukemia cells before and after differentiation: I. Characterization of spectrin-like proteins and increased association of actin

Two-step sucrose density gradient centrifugation was used to isolate the plasma membrane of a myeloid leukemia cell line (Ml). Calspectin (or fodrin) was identified in the Triton-insoluble fraction from the plasma membrane, and the molecular size and actin- and calmodulin-binding activity were studied. During differentiation of this cell line, which accompanied the induction of cell motility and phagocytic activity, the membrane-bound actin increased dramatically, whereas calspectin increased only slightly. Therefore, calspectin does not appear to have a major function in the increased binding of actin filaments to the plasma membrane, a requirement for the induction of cell motility.