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Biomedical subjects

M Aikawa

Publications and source records attributed to M Aikawa.

At least 307 records · Page 17Linked to original sources
PubMed1982

Interactions between macrophagelike cells and Leishmania braziliensis in vitro.

The interaction between macrophagelike cells (P388D murine tumor cells) and Leishmania braziliensis panamensis promastigotes was studied in vitro under various conditions by light and electron microscopy. When the macrophagelike cells and L braziliensis promastigate were incubated together for 2 minutes, 90% of the promastigotes were attached to the macrophagelike cells by the tip of the flagella. The macrophagelike cells did not form pseudopods or aggregated microfilaments around the inserted flagellum. After a 5-minute incubation period, the parasites attached to the macrophagelike cells did not show preferred orientation. At this time, numerous pseudopods and aggregated microfilaments of the macrophagelike cells were seen around the invading parasites. When the relationship between the cytochalasin B-treated promastigotes and the macrophagelike cells were examined, no interaction of the promastigote flagella with macrophagelike cells was observed at 2 minutes. After a 5-minute incubation period, 50% of the attached parasites adhered to a macrophagelike cell without any particular orientation. When the interaction between the promastigotes and cytochalasin B-treated macrophagelike cells were examined, the cytochalasin B-treated cells showed fewer pseudopods than the untreated cells, and the number of parasites attached to them was reduced considerably after a 5-minute incubation period. This data demonstrated, for the first time, that the mode of entry by Leishmania promastigotes into macrophagelike cells is dependent on the activation of the macrophagelike cells following the attachment of Leishmania promastigotes.

Animals↗
PubMed1981

Falciparum malaria-infected erythrocytes specifically bind to cultured human endothelial cells.

Erythrocytes infected with the late stages of the human malarial parasite Plasmodium falciparum became attached to a subpopulation of cultured human endothelial cells by knoblike protrusions on the surface of the infected erythrocytes. Infected erythrocytes did not bind to cultured fibroblasts; uninfected erythrocytes did not bind to either endothelial cells or fibroblasts. The results suggest a specific receptor-ligand interaction between endothelial cells and a component, components, in the knobs of the infected erythrocytes.

Animals↗
PubMed1981

Bovine babesiosis: protection of cattle with culture-derived soluble Babesia bovis antigen.

Adult Hereford (Bos taurus) cattle were protected from severe reactions and death caused by the tick-borne protozoan hemoparasite Babesia bovis, 3 months after vaccination with a cell culture--derived immunogen. The immunogen consisted of filtered, freeze-dried supernatant fluid collected from long-term cultures of Babesia bovis in vitro. It was reconstituted with saponin adjuvant and injected twice subcutaneously at 2-week intervals. Serum collected from vaccinated cattle caused thickening of the merozoite surface coat, aggregation, and lysis of merozoites in vitro. This reaction was identical to that caused by serum from immune carrier cattle suggesting that the protective antigen present in culture fluids is merozoite surface coat antigen. No mortality occurred among vaccinated cattle, whereas mortality among unvaccinated cattle and Babesia bigemina--immune cattle was 62.5 percent indicating that immunity to bovine babesiosis is species-specific.

Animals↗
PubMed1981

Neurosecretory granules in small cell invasive carcinoma of the urinary bladder.

A 69-year-old man showed symptoms of urinary bladder irritability and hematuria. Cystoscopy and radiographic studies revealed a tumor within a bladder diverticulum. The tumor shared histologic and ultrastructural features with oat cell carcinoma of the lung, including the presence of small numbers of neurosecretory type granules. In spite of conservative surgical treatment, there has been no evidence of recurrent or metastatic tumor over 14 months of follow-up. Hypophosphatemia was present preoperatively, but resolved spontaneously after tumor resection. In regard to histogenesis, a metaplastic origin is favored. This appears to be the first reported case of a neoplasm of Kultschitzky-type cells arising in the urinary bladder.

Aged↗
PubMed1981

Prostaglandin and thromboxane synthesis by rat glomerular epithelial cells.

Isolated rat glomeruli have been shown to synthesize prostaglandin (PG) and thromboxane (Tx). In this study, we evaluated, by radioimmunoassay and radiochromatographic methods, PG and Tx synthesis by glomerular cells in culture. Transmission and scanning electron microscopy showed polygonal cells, attached by desmosomes, with surface microvilli. These features are typical of glomerular epithelial cells. Incubation of these glomerular epithelial cells with arachidonic acid (C20:4) resulted in an array of endproducts with concentrations of PGE2 greater than TxB2 greater than PGF2 alpha greater than 6-keto-PGF1 alpha . Addition of angiotensin II (AII) to the cultured glomerular cell produced almost exclusive stimulation of PGE2 with PGE2 much much greater than PGF2 alpha greater than TxB2 = 6-keto-PGF1 alpha . AII and AIII (100 micrometer to 1 micrometer ) stimulated PGE2 in glomerular epithelial cells, and the increments of PGE2, as a function of the concentration of AII or AIII, were similar. The sar1-thr8-AII analog inhibited both AII- and AIII-stimulated PGE2 synthesis. The divalent cation ionophore A23187 in concentrations of 0.2 to 2.0 micrometer increased primarily PGE2 and TxB2 synthesis with smaller increases of PGF2 alpha and 6-keto-PGF1 alpha . The relative concentrations of PG and Tx produced by rat glomerular epithelial cells, incubated with C20:4 or A23187, were similar. Our results demonstrate that: (1) the predominant cell grown in culture from the rat glomerulus, after 9 days, is the epithelial cell; (2) this cell is capable of PG and Tx synthesis; (3) stimulation of PG by AII and AIII may be mediated by the same cellular receptor, AII and AIII increase primarily the synthesis of a vasodilatory PG, PGE2; (4) exogenous substrate C20:4 or release of endogenous C20:4 by the divalent cation ionophore A23187 not only stimulates PGE2 but also the vasoconstrictor TxA2; and (5) the PG and Tx endproducts synthesized by epithelial cells may be determined by an intracellular coupling of the specific synthetic enzymes with different pools of C20:4.

Angiotensins↗
PubMed1981

Freeze-fracture study on the erythrocyte membrane during malarial parasite invasion.

Invasion of erythrocytes by malarial merozoites requires the formation of a junction between the merozoite and the erythrocyte. Migration of the junction parallel to the long axis of the merozoite occurs during the entry of the merozoite into an invagination of the erythrocyte. Freeze-fracture shows a narrow circumferential band of rhomboidally arrayed particles on the P face of the erythrocyte membrane at the neck of the erythrocyte invagination and matching rhomboidally arrayed pits on the E face. The band corresponds to the junction between the erythrocyte and merozoite membranes observed in thin sections and may represent the anchorage sites of the contractile proteins within the erythrocyte. Intramembrane particles (IMP) on the P face of the erythrocyte membrane disappear beyond this junction. When the erythrocytes and cytochalasin B-treated merozoites are incubated together, the merozoite attaches to the erythrocyte membrane and a junction is formed between the two, but the invasion process does not advance further and no movement of the junction occurs. Although there is no entry of the parasite, the erythrocyte membrane still invaginates. Freeze-fracture shows that the P face of the invaginated erythrocyte membrane is almost devoid of the IMP that are found elsewhere on the membrane, suggesting that the attachment process in and of itself is sufficient to create a relatively IMP-free bilayer.

Animals↗
PubMed1981

A simple and effective method for hemolysis with a hypoxanthine-xanthine oxidase system and alteration of erythrocyte phospholipid composition during the hemolysis.

A very rapid hemolysis was found to be caused by active oxygen species produced by a hypoxanthine-xanthine oxidase system with very low concentrations of hypoxanthine. The addition of superoxide dismutase or catalase inhibited the hemolysis, indicating that O2- and H2O2 participate in this system. The extent of erythrocyte hemolysis was found to depend on the sex of the human donor. The change in phospholipid composition before and after hemolysis in human erythrocytes from donors of each sex was compared by thin layer chromatography. A significant decrease in phosphatidylethanolamine content and a concomitant increase in altered phospholipid fraction were observed in erythrocytes from male donors, suggesting that these erythrocytes were easily attacked by active oxygen species to produce modified phosphatidylethanolamine.

Adult↗
PubMed1981

Transmission and scanning electron microscopic studies of the micronemata of Trypanosoma gambiense.

The structure of micronemata arising from the surface of the bloodstream form of Trypanosoma gambiense was studied by electron microscopy. In order to produce micronemata, trypanosomes were incubated in either 1) phosphate buffered saline supplemented with glucose (PBSG), 2) immune mouse serum or 3) PBSG after passage through a DEAE-cellulose column. Electron microscopic examination of the parasite revealed the presence of thread-like micronemata arising from the anterior end and from the flagellar pocket regardless of the incubation conditions. Negative staining revealed a distinct peripheral fringe layer with nodular protrusions covering the entire surface of the micronema. The distribution and number of intramembrane particles (IMP) on the P and E faces of the micronema were similar to those of the flagellum of T. gambiense, indicating a close relationship between the membrane structure of the micronema and the flagellum. Micronemata became fragmented and adhered to each other after incubation of the parasite in the media for 12 h. Since micronemata tend to have the characteristics of adhesiveness and fragmentation, fragments of these structures might adhere to various host organs. Dispersal of potential antigenic material might be responsible, in part, for the induction of the host immune response.

Adhesiveness↗
PubMed1981

An electron microscopical study of the interaction of monoclonal antibodies with gametes of the malarial parasite Plasmodium gallinaceum.

Anti-malarial gamete antibodies prevent the fertilization of gametes in the mosquito midgut and prevent transmission of malaria. Recently, hybridoma cell lines secreting monoclonal antibodies (10G3 and 11C7) against gametes of the malarial parasite have been developed. These antibodies act synergistically to mediate 80--90% suppression of the infectivity of gametocytes, although neither monoclonal antibody alone has a significant effect on gametocyte infectivity. We performed immuno-electron microscopy to characterize the interactions of these monoclonal antibodies with gametes of Plasmodium gallinaceum. Male gametes exposed to either 10G3 or 11C7 agglutinated into loose clusters, while those exposed to a mixture of 10G3 and 11C7 agglutinated into long, rope-like bundles. This difference appears to be related to the distribution of the antibodies on the surface of the gametes. When 10G3 or 11C7 labeled with a ferritin-conjugated anti-mouse Ig were used singly, the ferritin particles were distributed in focal areas over the surface of the parasites. By contrast, when the male gametes were exposed to a mixture of 10G3 and 11C7, the ferritin particles were distributed over their entire surface. Female gametes reacted similarly to these antibodies. These observations indicate that combinations of antibody specificities that reduce fertilization efficiency coat the entire surface of the gametes. On the other hand, focal interactions resulting from a single antibody are unable to block fertilization.

Agglutination↗
PubMed1981

Inhibitory effects of immune monkey serum on synchronized Plasmodium falciparum cultures.

We studied the effects of heat-inactivated immune monkey serum on the growth of a partially synchronized culture of Plasmodium falciparum. By light microscopy, parasites within erythrocytes were morphologically indistinguishable from those cultured in normal serum. Immune serum reduced by 90% the number of erythrocytes containing newly invaded rings. Clusters of extracellular merozoites, usually around clumps of malarial pigment, were seen frequently in cultures grown with immune serum but rarely in cultures with normal serum. Electron microscopy confirmed the normal development of intraerythrocytic parasites. In immune serum cultures, electron-dense precipitates were found on the surface of schizonts, merozoites, and the excrescences on the plasma membrane of schizont-infected erythrocytes. Merozoites in immune serum culture appeared to aggregate by adherence between adjacent surface coats. These findings support the hypothesis that immune serum agglutinates merozoites and thereby inhibits their invasion into uninfected erythrocytes.

Animals↗
PubMed1981

Monoclonal antibodies against a specific surface determinant on malarial (Plasmodium knowlesi) merozoites block erythrocyte invasion.

Twelve hybridoma cell lines secreting monoclonal antibodies against Plasmodium knowlesi merozoites have been produced. Antibodies from 3 of the 12 lines agglutinated merozoites. The 2 monoclonal antibodies (13C11 and 16F8) that markedly agglutinated merozoites blocked merozoite invasion of erythrocytes. Of these 2 lines, the one that induced the most agglutination also blocked invasion most effectively. The third monoclonal antibody (53B3) caused minimal agglutination of merozoites and did not block invasion, nor did the other 9 nonagglutinating antibodies. The 2 blocking monoclonal antibodies bound to antigens around the entire surface of merozoites, as demonstrated by immunoelectron microscopy, and precipitated a single biosynthetically labeled protein of apparent m.w. of 250,000. None of the nonagglutinating lines precipitated this protein. Monoclonal antibodies 13C11 and 16F8 reacted with a common antigenic determinant on a Malaysian and a Philippine strain of P. knowlesi in that they blocked invasion and precipitated a 250,000 m.w. protein from both. Sera from immune monkeys also precipitated this 250,000 m.w. protein.

Agglutination↗
PubMed1981

Dirofilariasis. IV. Glomerulonephropathy induced by Dirofilaria immitis infection.

The kidneys of dogs chronically infected with Dirofilaria immitis were studied by light, electron, and immunofluorescent microscopy. The glomeruli of dogs with high microfilaremia showed a moderately increased mesangium and thickened glomerular basement membrane. There was a deposition of electron-dense particles which were continuously distributed in the lamina rara interna and lamina densa of the glomerular basement membrane. Immunofluorescent microscopy showed intense IgG deposits in a uniform linear pattern along the glomerular basement membrane. This linear deposition of IgG appeared to correspond to continuous distribution of electron-dense particles in the basement membrane. Microfilariae present in the glomerular capillary lumens were connected with the capillary endothelial cells by narrow cytoplasmic bands. The interaction of the worm's internal substances with the glomerular capillaries through these cytoplasmic bands may deposit worm antigen on the glomerular capillary wall before antigen-antibody interaction takes place. These findings suggest that the glomerulopathy seen in dogs infected with D. immitis is caused by the in situ formation of immune complexes in the glomerular basement membrane.

Animals↗
PubMed1981

The protective antigen of malarial sporozoites (Plasmodium berghei) is a differentiation antigen.

Pb44, the protective antigen of rodent malaria sporozoite (Plasmodium berghei) covers the entire surface of mature, salivary gland sporozoites. This antigen is undetectable in approximately 50% of the immature, i.e., oocyst sporozoites. On the surface of the remaining oocyst sporozoites, Pb44 is found in patches. Pb44 is present in early exoerythrocytic liver stages of P. berghei but is present in early exoerythrocytic liver stages of P. berghei but becomes undetectable after 30 hr of intrahepatocytic development. It seems likely that Pb44 is a differentiation antigen associated with an unique function of the sporozoites, perhaps penetration in the target host cells.

Animals↗
PubMed1981

Therapeutic effectiveness of frozen platelet concentrates for transfusion.

Six patients received platelet concentrate transfusions from their HLA-identical siblings. Platelet concentrates were administered either fresh, or after being frozen in 10% dimethylsulfoxide, at a slow controlled rate (1 degree C/min) or rapidly (approximately 8 degrees C/min) in the vapor-phase of a liquid nitrogen refrigerator. The median freeze-thaw loss was 13.5%. The mean 1-hr and 20-hr corrected increments in platelet count were calculated for fresh platelet concentrates transfused before and after transfusion with controlled-rate frozen and vapor-phase frozen platelet concentrates. There was no significant difference among the first and second transfusion of fresh platelet concentrates, nor was the difference observed between fresh and controlled-rate frozen platelet concentrates significant. The difference between fresh and vapor-phase frozen platelet concentrates, and between controlled-rate frozen and vapor-phase frozen platelet concentrates were highly significant (p < 0.01). In vitro tests of aggregation using ristocetin and platelet ultrastructural studies paralleled the transfusion experience. Our results indicate that HLA-identical platelet concentrates can be successfully frozen and thawed for transfusion if a slow, controlled rate of freezing is employed. The use of HLA-identical frozen platelet concentrates may be important in emergency situations for the refractory patient and potentially for the establishment of a platelet concentrate bank.

Anemia, Aplastic↗
PubMed1981

Dirofilaria immitis. 5. Immunopathology of filarial nephropathy in dogs.

Fourteen beagles infected with larvae (microfilariae) of Dirofilaria immitis, were randomly selected from another study in which the toxic effects of subfilaricidal doses of diethylcarbamazine were being evaluated. This group of 14 dogs, together with 4 uninfected control animals, were variably sacrificed between 14 and 25 months after larval inoculations, and the ensuing renal lesions were studied by light and ultrastructural microscopy and by immunofluorescence and antibody elution techniques. On the basis of these studies, two groups of animals were distinguished. The first group was characterized by a striking pattern of linear fluorescence and fine ultrastructural dense deposits along the glomerular basement membrane, poor antibody response, and an inability to clear microfilariae from the tissues and circulation. The second group, with a nonlinear pattern of fluorescence, was characterized by a strong immune response, efficient elimination of microfilariae, and immunofluorescence and ultrastructural evidence of predominantly mesangiopathic immune complex renal disease. In both groups, elution studies demonstrated tissue deposits of antiworm antibodies, suggesting a filaria-antibody immune-complex nephropathy. No evidence was found for the presence of anti-basement-membrane antibodies. On the basis of a previous experimental model, it is postulated that in the first group of animals with linear fluorescence, the observed lesions may represent a natural form of an immunopathogenic mechanism of glomerular damage in which filarial antigen becomes uniformly localized in the glomerulus and elicits an autologous antibody response. The possible role of the drug diethylcarbamazine in inducing this mechanism of immune injury is discussed.

Animals↗
PubMed1980

Hybridoma produces protective antibodies directed against the sporozoite stage of malaria parasite.

Hybrid cells secreting antibodies against sporozoites of Plasmodium berghei were obtained by fusion of plasmacytoma cells with immune murine spleen cells. The monoclonal antibodies bound to a protein with an apparent molecular weight of 44,000 (Pb44), which envelopes the surface membrane of sporozoites. Incubation of sporozoites in vitro with antibodies to Pb44 abolished their infectivity.

Animals↗