PubMed Health⌕ Search

Biomedical subjects

F Sendo

Publications and source records attributed to F Sendo.

At least 37 records · Page 2Linked to original sources
PubMed1998

Multiple gene duplication and expression of mouse bcl-2-related genes, A1.

Here we report the genomic cloning and characterization of the murine A1 genes, which belong to the bcl-2 gene family. Southern analysis indicated the existence of at least four A1 genes in the murine genome and four different A1 genes, designated A1-a, -b, -c and -d, were cloned from the murine genomic library. The A1-a, -b and -d genes consisted of two exons, whereas the A1-c gene contained 1 bp insertion in the coding region which may result in an aberrant and truncated protein by frame-shift. With the exception of A1-c, the coding regions among A1 genes are highly conserved at >97% at the nucleotide level and at >96% at the amino acid level. A1-a, -b and -d genes appeared to be expressed specifically in organs containing many neutrophils. In neutrophils, A1-a, -b and -d transcripts were detected at a comparable level. Our data suggest that the multiple A1 genes in mice were generated by gene duplication and each of them may function as anti-apoptotic molecules in neutrophils.

Amino Acid Sequence↗
PubMed1997

Nitric oxide is an effector molecule in inhibition of tumor cell growth by rIFN-gamma-activated rat neutrophils.

This study was designed to determine the effector molecule responsible for the tumor-inhibitory activity of rat neutrophils treated with rat recombinant interferon gamma (rIFN-gamma) in vitro. The results show that nitric oxide (NO) production by neutrophils is dependent on rIFN-gamma concentration, and that neutrophil-mediated tumor cytostasis is in turn dependent on the amount of NO. NO production and tumor cytostasis by rIFN-gamma-activated neutrophils were inhibited completely by N(G) monomethyl-L-arginine (NGMMA), a specific competitive NO production inhibitor. Tumor cytostasis was also inhibited by oxyhemoglobin (HbO(2)), an NO scavenger. An extracellular oxygen radical scavenger, superoxide dismutase (SOD), was found to increase tumor cell inhibition by rIFN-gamma-activated neutrophils by a factor of 4. This SOD-enhanced cytostasis was not even inhibited by catalase. Tumor cytostasis was slightly increased by a hydroxyl radical-(.OH) scavenger, dimethylthiourea (DMTU), which did not affect NO production by rIFN-gamma-activated neutrophils. Our findings suggest that tumor cytostasis of neutrophils activated by rIFN-gamma is mediated by L-arginine-derived nitrogen oxidation products, and that O(2)- produced by these neutrophils reduces NO-mediated tumor cytostasis at low NO concentrations.

Animals↗
PubMed1997

rIFN-gamma-activated rat neutrophils induce tumor cell apoptosis by nitric oxide.

We have previously shown that 1) neutrophils activated with various cytokines, including rat recombinant interferon gamma (rIFN-gamma), inhibit tumor cell growth and that 2) nitric oxide (NO) is the effector molecule in tumor inhibition by rIFN-gamma-stimulated rat peritoneal exudate neutrophils. In this study, we examined the nature of tumor cell death induced by rat peritoneal neutrophils activated by rIFN-gamma in order to clarify the mechanism of apoptosis in neoplastic tumor cell death. DNA of 3 syngeneic rat tumor cell lines was significantly fragmented within 3 hr of incubation in the presence of rIFN-gamma-activated neutrophils, and this effect was dependent on both the concentration of rIFN-gamma and the number of neutrophils. This DNA fragmentation was inhibited by L-N-(I-iminoethyl)-ornithine (L-NIO), a NO synthase inhibitor, but not by superoxide dismutase (SOD). Tumor cells treated with the activated neutrophils were shown by electron microscopy to be apoptotic, exhibiting necrotic features with a longer incubation. On the other hand, cytolysis of tumor cells, as determined by a [3H]-uridine release assay, was first observed only at 24 hr of incubation with the rIFN- gamma-activated neutrophils. Taken together, our results suggest that tumor cell apoptosis by activated neutrophils is NO-dependent and that apoptotic tumor cells undergo necrosis as a secondary process. We suggest that tumor cell apoptosis induced by activated neutrophils plays an important role in regulation of neoplastic tumor cell growth and death in vivo.

Animals↗
PubMed1997

Apoptosis and in vivo distribution and clearance of eosinophils in normal and Trichinella spiralis-infected rats.

We examined apoptosis of eosinophils obtained from normal rats and rats infected with Trichinella spiralis (T. spiralis). A considerable percentage of normal rats underwent apoptosis within a few hours, however, the apoptosis rate of infected rats was significantly lower. This rate began decreasing only 12 h after infection, reached its lowest level on day 3, and was restored to normal by day 40. We also studied the effects on eosinophil apoptosis of culture supernatants from concanavalin A-stimulated spleen cells from infected rats and found that supernatants from days 3, 7, and 18 of infection inhibited apoptosis eosinophils from normal rats. We then examined the distribution and clearance of eosinophils in vivo. In normal rats, the largest numbers of eosinophils were found in the spleen, liver, and bone marrow. In the infected rats, however, by day 3, by which time the worms had begun to migrate, there was a striking increase in these cells in the intestines. In summary, normal eosinophils are unexpectedly sensitive to apoptosis, whereas infected eosinophils become resistant to this form of cell death.

Animals↗
PubMed1997

External calcium-dependent, F-actin-independent and pertussis toxin-insensitive novel neutrophil locomotion induced by a mAb.

We previously demonstrated that a mAb to human neutrophils, designated 3H9, which was established by screening for inhibition of neutrophil adherence to plastic plates containing fetal bovine serum, enhanced both n-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced chemotaxis and random migration of neutrophils. In the present study, we examined the mechanisms of 3H9-induced enhancement of neutrophil locomotion in the phagokinetic track assay. 3H9-induced neutrophil locomotion maintained a straight path which was different from the track resulting from FMLP-stimulated locomotion. This 3H9-induced migration required extracellular Ca2+. beta 2-Integrin activation was a prerequisite for the increase in cytosolic free calcium induced by 3H9 treatment. However, stimulation by 3H9 did not induce an increase in F-actin, even after CD18 activation. Signal transduction after molecular recognition by 3H9 was not mediated by pertussis toxin-sensitive, heterotrimeric G proteins. These results suggest that 3H9 enhances neutrophil migration by mechanisms which are different from those involved in usual chemoattractant-induced migration. Neutrophil surface molecules recognized by 3H9 may play a crucial role in the regulation of transendothelial migration of leukocytes.

Actins↗
PubMed1997

A monoclonal antibody modulates neutrophil adherence while enhancing cell motility.

A monoclonal antibody (MoAb) to human neutrophils, designated 3H9, was established by screening for the inhibition of neutrophil adherence to plastic plates containing a medium supplemented with fetal calf serum (FCS medium). The antigen recognized by 3H9 was shown to be present on human leukocytes and found at the highest levels on granulocytes. On Western blotting, 3H9 reacted with a molecule having a molecular weight of 80 kDa. When this MoAb was added at the same time as a neutrophil stimulant (fMLP), the inhibition of neutrophil adherence to plastic plates in the presence of FCS medium was observed after 60 min incubation. Furthermore, this MoAb enhanced not only fMLP-induced chemotaxis but random migration of neutrophils as well. The mechanisms of these phenomena are discussed.

Animals↗
PubMed1997

Selective depletion of neutrophils by a monoclonal antibody, RP-3, suppresses dextran sulphate sodium-induced colitis in rats.

Administration of dextran sulphate sodium to animals induces acute colitis characterized by infiltration of large numbers of neutrophils into the colonic mucosa, which histologically resembles human active ulcerative colitis. It has been reported that neutrophils and the reactive oxygen metabolites produced by them are involved in the progress of ulcerative colitis. This study was intended to clarify their roles by using this animal model. First, possible sources and species of reactive oxygen metabolites were determined using luminol-dependent chemiluminescence with addition of enzyme inhibitors and reactive oxygen metabolite scavengers. Next, to examine whether neutrophils and hypochlorous acid derived from them contribute to tissue injury, we administered RP-3, a monoclonal antibody capable of selectively depleting neutrophils, and taurine, a hypochlorous acid scavenger, to rats treated with dextran sulphate sodium. Addition of azide, taurine, catalase, superoxide dismutase and dimethyl sulphoxide into colonic mucosal scrapings significantly inhibited chemiluminescence production, but allopurinol and indomethacin had no effects. These results suggest that excessive hypochlorous acid, hydrogen peroxide, superoxide anion and hydroxyl radical are generated by the inflamed colonic mucosa. Intraperitoneal injections of RP-3 significantly suppressed bleeding, tissue myeloperoxidase activity, chemiluminescence production and erosion formation. On the other hand, administration of taurine tended to inhibit bleeding and erosion formation to some extent, although it could not significantly suppress them. These data suggest that neutrophils play an important role in the development of this colitis and that hypochlorous acid might be one of the causes of tissue injury induced by neutrophils.

Animals↗
PubMed1996

Enhancement of delayed-type hypersensitivity to sheep red blood cells in mice by granulocyte colony-stimulating factor administration at the elicitation phase.

We previously demonstrated that selective depletion of polymorphonuclear neutrophils by a mAb inhibits both the priming and effector phases of delayed-type hypersensitivity (DTH) to SRBC. To better understand the role of polymorphonuclear neutrophils in DTH, we examined the effect of granulocyte CSF (G-CSF) on DTH to SRBC in mice. G-CSF administered at the elicitation phase enhanced a DTH response that was weak in control G-CSF-untreated mice. This treatment also augmented mononuclear leukocyte recruitment in DTH in these mice. However, G-CSF administration failed to augment priming of DTH to SRBC under any conditions examined.

Animals↗
PubMed1996

Rapid killing of human neutrophils by the potent activator phorbol 12-myristate 13-acetate (PMA) accompanied by changes different from typical apoptosis or necrosis.

To elucidate the relationship between activation of neutrophils and their subsequent death, the effect of phorbol 12-myristate 13-acetate (PMA), a potent activator of neutrophils, was examined. PMA-treated neutrophils showed morphological changes quite different from those of typical apoptosis or necrosis. After fusion of the lobate nucleus, nuclear contents of chromatin uniformly decreased in compactness and soon after the nuclear envelope was broken. Even at this stage, cytoplasmic organelles did not undergo degeneration. Membrane permeability began increasing at 3 h of incubation with PMA, subsequent to nuclear change. Conventional agarose gel electrophoresis and pulsed field gel electrophoresis of DNA from PMA-treated neutrophils revealed no DNA degradation products smaller than 300 kbp. PKC inhibitors, staurosporine and H-7, prevented cytotoxicity by PMA. Furthermore, antioxidants, thiourea, dimethylthiourea, pyrrolidinethiocarbamate, and N-acetyl-L-cysteine, but not superoxide dismutase, were also active in preventing PMA cytotoxicity, suggesting that cell suicide resulting from PMA treatment is due to oxygen radicals, especially the hydroxyl radical. A certain population of neutrophils phagocytosing opsonized zymosan also showed changes similar to those observed in PMA-treated cells.

Antioxidants↗
PubMed1996

The neutrophil as an information transmitter in tumor inhibition by a streptococcal biological response modifier, OK-432.

Effective treatment of a rat transplanted ascites tumor by i.p. injection of a streptococcal biological response modifier, OK-432, was abrogated by selective in vivo depletion of neutrophils by a monoclonal antibody, RP-3. The mechanisms by which neutrophils participate in the therapeutic action of OK-432 were studied with Winn's assay using peritoneal exudate cells periodically obtained from rats i.p. injected with this biological response modifier. Intraperitoneal resident macrophages were first activated with OK-432, and within 3 h, tumor-inhibitory activity had moved to the early exuded neutrophils. However, 6 h after injection, exuded macrophages were the only cells involved in tumor inhibition. Considered together with other findings, it is likely that, in this system, neutrophils may transmit information from resident macrophages to exuded inflammatory macrophages in a series of responses induced by i.p. injection of OK-432.

Animals↗
PubMed1996

Reduced anti-Pseudomonas aeruginosa activity of a cephalosporin, cefodizime, in rats whose neutrophils were selectively depleted by a monoclonal antibody.

In order to clarify the mechanisms of the in vivo antibacterial activity of a cephalosporin, cefodizime (CDZM), the effect of this antibiotic on Pseudomonas aeruginosa E7 infection was examined in rats whose neutrophils had been selectively depleted by monoclonal antibody RP-3. CDZM was less effective in RP-3-treated rats than in untreated rats. However, treatment of rats with recombinant human granulocyte-colony stimulating factor (rhG-CSF) augmented the in vivo activity of this antibiotic. Furthermore, the in vivo antibacterial activity of two other cephalosporins, cefpimizole (CPIZ) and cefoperazone (CPZ), was bilaterally affected by a rise or fall in the neutrophil number, although to a lesser degree than was the case with CDZM. Taken together, neutrophils play an important role in the in vivo antibacterial activity of certain cephalosporins.

Animals↗
PubMed1996

Involvement of two types of TNF receptor in TNF-alpha induced neutrophil apoptosis.

We previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) induces rapid human neutrophil apoptosis. In this paper, we examined which of the TNF receptors, p55 kDa TNF receptor (55-R) or p75 kDa TNF receptor (75-R), or both are involved in this process using specific rabbit antisera. Antibodies to 55-R (anti55-R) or 75-R (anti75-R) alone did not induce neutrophil apoptosis. Further addition of cycloheximide and anti-rabbit immunoglobulin to anti55-R but not to anti75-R accelerated apoptosis, although anti75-R augmented the capacity of anti55-R to do so. These results suggest that 55-R is a prerequisite for TNF-alpha induced neutrophil apoptosis.

Animals↗
PubMed1996

Role of neutrophils in the pathogenesis of experimental vasculitis.

In the Brown-Norway rat, mercuric chloride (HgCl2) induces an autoimmune syndrome characterized by high IgE levels. There is widespread necrotizing leukocytoclastic vasculitis involving lung, skin, mucous membranes, pancreas, liver, and gut, with tissue injury being most marked in the cecum. As in systemic vasculitis in man, there are neutrophils at the site of tissue injury and the animals develop anti-neutrophil cytoplasmic antibodies, which in the Brown-Norway rat are directed against myeloperoxidase. To determine whether neutrophils are involved in the pathogenesis of the vasculitis, we have used a monoclonal antibody that was reported to deplete neutrophils in other rat strains. Rats treated with HgCl2 received antibody by intravenous injection at various time points. Serial blood samples were taken for neutrophil counts and to assay for anti-myeloperoxidase and IgE antibodies. The guts of animals killed after antibody therapy were scored for vasculitic changes and neutrophils infiltrate. RP3 (but not the control antibody MAC6) was shown to bind to Brown-Norway rat neutrophils and to block glycogen-induced influx of neutrophils into the peritoneum. When given at peak disease, RP3 caused a dose-dependent reduction in tissue injury with a marked reduction in circulating blood neutrophil numbers and in tissue neutrophil infiltrate. RP3 treatment did not affect the rise in titer of IgE and anti-myeloperoxidase antibodies. The data presented demonstrate that in this model neutrophils are necessary for the induction of vasculitis and that the degree of vasculitis correlates with neutrophil number. To our knowledge, this study is the first to provide direct evidence for a role for neutrophils in vasculitis. We suggest that antibodies directed against neutrophils, especially if they deplete neutrophils, may be useful in the therapy of vasculitis in man.

Animals↗
PubMed1996

[TNF/TNFR gene and apoptosis].

Intracellular signal transduction pathways induced by in the reaction of TNF and TNF receptors has been clarified through finding of various TNF receptor associated intracytoplasmic molecules. The possible role of these signal transduction pathways for apoptosis induced by TNF is discussed.

Amino Acid Sequence↗
PubMed1996

Regulation of neutrophil apoptosis--its biological significance in inflammation and the immune response.

Neutrophils play a pivotal role in host defence against bacterial infection. Their life span is short compared with that of leukocytes of other lineages. Neutrophils are programmed to die by apoptosis at the time of differentiation. However, recent studies have demonstrated that environment also has a great influence on apoptosis of these cells. Based on our recent experimental results, we present here a review of studies on the regulation of neutrophil apoptosis and discuss its biological significance in inflammation and the immune response.

Animals↗
PubMed1996

Immunohistochemical localization of Gnathostoma spinigerum larval antigens by monoclonal antibodies: II. Electron microscopy.

Immunocytochemical localization of antigens in advanced third-stage larvae of Gnathostoma spinigerum (GsAL3) was studied by immunogold labeling method using seven G. spinigerum specific monoclonal antibodies (MAbs), FS-3D11, SS-5H5, SK-6C4, SK-4E1, SK-7G6, SK-8D4 and SA-9B5. All these MAbs belong to the IgG1 subclass and only FS-3D11 and SS-5H5 recognize carbohydrate epitopes. The paraformaldehyde-fixed GsAL3 were embedded in Lowicryl K4M medium, and the gold colloidal particles used were 15 nm in size. When the worm sections were probed with FS-3D11, the gold particles appeared to concentrate specifically on the intestinal brush border. When SS-5H5 was applied, the particles were scattered densely over the brush border and in the cytoplasm of epithelial cells. The rest of the MAbs which recognize protein determinants exhibited a lack of labeling. The results suggested that the carbohydrate antigenic determinants recognized by the two MAbs are the most stable and most abundant particularly in the intestine of GsAL3. These results also confirmed the previous finding that the most antigenic site of GsAL3 is the intestine.

Animals↗
PubMed1995

In vivo regulation of rat neutrophil apoptosis occurring spontaneously or induced with TNF-alpha or cycloheximide.

We previously demonstrated that human TNF-alpha induces rapid apoptosis of human neutrophils. To understand better the in vivo significance of neutrophil apoptosis, we examined spontaneous, recombinant human and mouse TNF-alpha- or cycloheximide-induced apoptosis of normal peripheral blood neutrophils (PBN), PBN from rats injected i.p. with proteose peptone or a streptococcus preparation, OK-432 (inflammatory PBN), peritoneally exudated neutrophils (PEN) obtained after a proteose peptone injection, and normal bone marrow neutrophils. The following observations were made. 1) Normal PBN responded to TNF-alpha, but PEN, normal bone marrow neutrophils, and inflammatory PBN at 12 h after stimulation did not. 2) The sensitivity to TNF-alpha of the inflammatory PBN started to decrease at 3 h, was lowest at 12 h, and was almost restored at 52 h after stimulation. 3) Spontaneous apoptosis of normal and inflammatory PBN reached 25% at 12 h after in vitro incubation, but that of PEN and normal bone marrow neutrophils was very low over this period. 4) The sensitivity to cycloheximide (6 h incubation) was high for normal PBN and bone marrow neutrophils, but low for PEN and inflammatory PBN after 12 h. 5) 125I-rhTNF-alpha binding of bone marrow neutrophils was significantly lower than that of normal and inflammatory PBN and PEN. 6) TNF-alpha-induced apoptosis of normal or inflammatory PBN and bone marrow neutrophils was enhanced by treatment with low doses of cycloheximide that alone were barely able to induce neutrophil apoptosis; however, apoptosis of PEN was not. The mechanisms and in vivo significance of these phenomena are discussed.

Animals↗