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Biomedical subjects

T Yasuda

Publications and source records attributed to T Yasuda.

At least 865 records · Page 48Linked to original sources
PubMed1983

Activation of the alternative complement pathway by IgM antibody reacted on paragloboside incorporated into liposome membrane.

Liposomes containing paragloboside (PG) on their membrane were readily lysed by C4 deficient guinea pig serum (C4D-GPS). On the other hand, guinea pig serum from specific pathogen free Hartley guinea pigs (SPF-GPS) did not lyse PG-liposomes in Mg-EGTA-GVB (gelatin veronal buffered saline containing MgCl2 and ethyleneglycol-bis(beta-aminoethyl ether)N,N'-tetraacetate) which permits complement activation via the alternative pathway but not via the classical pathway. However, the SPF-GPS could lyse the liposomes in Mg-EGTA-GVB when heated (56 degrees C, 30 min) C4D-GPS or other guinea pig serum (GPS) was added. Gel filtration of Hartley (Htl)-GPS through a Sephadex G-200 column revealed that IgM antibody to PG in Htl-GPS was responsible for sensitization of the liposomes to lysis by complement of SPF-GPS via the alternative pathway. This result indicated that guinea pig IgM antibody can initiate the activation of the alternative pathway of homologous complement on liposome membrane.

Animals↗
PubMed1983

Differing reactivities of human and guinea-pig complement on haptenized liposomes via the alternative pathway.

Several haptens coupled to dipalmitoylphosphatidylethanolamine (DPPE) were inserted into the liposome membrane with a base composition of an equimolecular mixture of dimyristoylphosphatidylcholine (DMPC) and cholesterol (Chol). Haptens used were trinitrophenyl (TNP)-DPPE, TNP-aminocaproyl (TNP-Cap)-DPPE, dinitrophenyl (DNP)-DPPE, DNP-aminocaproyl (DNP-Cap)-DPPE, fluoresceinthiocarbamyl (Fl)-DPPE, azobenzenarsonate-tyrosyl (ABA-Tyr)-DPPE, dansyl (DNS)-DPPE, dabsyl (DABS)-DPPE, dithiopyridyl (DTP)-DPPE and maleimidobenzoyl (MB)-DPPE. Reactivity of those haptenized liposomes with complement via the alternative pathway was assessed by release of trapped fluorescent marker from the liposomes following incubation with dilutions of guinea-pig and human sera in a diluent containing MgCl2 and ethyleneglycol-bis(beta-aminoethyl ether)N,N'-tetraacetate (EGTA). In the diluent (Mg-EGTA-GVB), complement activation via the alternative pathway proceeds while that via the classical pathway is inhibited. Fl-liposomes were found to be extremely sensitive to guinea-pig complement, being lysed by guinea pig serum dilutions of up to 1:76 in Mg-EGTA-GVB. Guinea-pig serum could lyse TNP-Cap-liposomes, DNP-Cap-liposomes, TNP-liposomes, DTP-liposomes, MB-liposomes, DNP-liposomes and ABA-Tyr-liposomes, with the reactivity of the liposomes decreasing in this order. However, the only haptenized liposomes sensitive to human serum in Mg-EGTA-GVB were DTP- and MB-liposomes; the other liposomes including Fl-liposomes being unreactive via the alternative pathway in reaction with human complement.

Animals↗
PubMed1983

Interaction of hapten-sensitized liposomes with cells bearing hapten-specific receptors.

The binding of liposomes sensitized with 2,4-dinitrophenyl-6-N-aminocaproylphosphatidylethanolamine (DNP-Cap-PE) to MOPC-315 cells, which secrete and bear on their surfaces anti-DNP immunoglobulins, was studied. The binding was affected by cholesterol content, phospholipid composition and hapten density of liposomes: The binding of distearoylphosphatidylcholine liposomes sensitized with 5 mol% hapten to the cells increased with increasing cholesterol content in liposomes. The amount of liposomes composed of phospholipid with a higher transition temperature (such as distearoylphosphatidylcholine), which bound to MOPC-315 cells, was much higher than that of liposomes composed of phospholipid with a lower transition temperature (such as egg yolk phosphatidylcholine). The amount of distearoylphosphatidylcholine liposomes containing equimolar cholesterol, which bound to the cells at 0 degrees C, increased with increasing amount of the hapten in liposomes up to 2.5 mol%. The binding became maximum at 2.5 mol% and decreased with higher hapten density in liposomes. The immunogenicity of hapten-sensitized liposomes is known to be affected by the liposomal composition such as cholesterol content, phospholipid composition and hapten density. This model study suggests that the binding of liposomes to cells is important for expressing the immunogenicity of hapten-sensitized liposomes.

Animals↗
PubMed1983

Interactions of beta-lactam antibiotics and antineoplastic agents.

The in vitro interactions of four beta-lactam antibiotics and five antineoplastic agents were examined with 100 clinically isolated strains of four species of gram-negative bacilli. Generally, by the checkerboard dilution method, beta-lactam antibiotics, when tested in combination with mitomycin C, bleomycin, or 5-fluorouracil, showed synergistic action, whereas when tested in combination with carboquone, they showed antagonistic action. Almost no combinations of adriamycin showed the interactions. Among beta-lactam antibiotics, piperacillin was more frequently synergistic than cefoperazone, cefazolin, or carbenicillin when tested in combination with each antineoplastic agent against various species.

Anti-Bacterial Agents↗
PubMed1983

Induction of cephalosporinase production by various penicillins in enterobacteriaceae.

The inducer activity of seven penicillins for cephalosporinase (CSase) production and their antibacterial activity against CSase-producing strains were studied using clinical isolates of Proteus morganii, P. rettgeri, P. vulgaris, Enterobacter cloacae, and Serratia marcescens. Piperacillin, apalcillin, and methicillin showed rather low inducer activity for CSase production in all strains tested. On the other hand, ampicillin, carbenicillin, and sulbenicillin showed high inducer activity for CSase production. Piperacillin, apalcillin, and ampicillin were less stable to CSases than were carbenicillin, sulbenicillin, and methicillin, but much more stable than benzylpenicillin. In the growing culture of CSase-producing strains, piperacillin and apalcillin were rather stable. Against CSase-producing strains, piperacillin and apalcillin were more active than other penicillins tested.

Cephalosporinase↗
PubMed1983

Activation of the alternative complement pathway by natural antibody to glycolipids in guinea-pig serum.

Liposomes containing paragloboside (PG) on their membrane were readily lysed by C4-deficient guinea-pig serum (C4D-GPS) through activation of the alternative complement pathway (ACP). Therefore we examined the reactivity of several types of guinea-pig serum (GPS) on PG-liposomes and determined that all GPS except that from specific pathogen-free (SPF) Hartley guinea-pigs had lytic capacity in Mg-EGTA-GVB (gelatin veronal-buffered saline containing Mg++ and ethyleneglycol-bis(beta-aminoethyl ether)N,N'-tetraacetate). This lytic capacity of GPS corresponded with the amount of natural antibody to PG in those sera. Although GPS of SPF guinea-pigs (SPF-GPS) could not lyse PG-liposomes in Mg-EGTA-GVB, it could lyse the liposomes when heated C4D-GPS or Hartley GPS was added. Natural antibody to PG in the heated sera was regarded to have sensitized PG-liposomes to lysis by SPF-GPS via ACP activation. Since the antibody to PG-liposomes was removed by lacto-N-nor-hexaosylceramide which has the same chemical structure in the terminal oligosaccharide, the antibody to PG in GPS was suggested to have a specificity to the terminal structure of oligosaccharide shared by lacto-N-nor-hexaosylceramide. Furthermore, the IgM fraction, which had been prepared by gel filtration of heated C4D-GPS on a Sephadex G200 column, could also sensitize PG-liposomes to lytic reaction of SPF-GPS in Mg-EGTA-GVB. This sensitizing capacity of heated C4D-GPS was suppressed by absorption of the serum or its IgM fraction with anti-guinea-pig mu-chain antibody coupled to Sepharose. Therefore, it was concluded that the lysis of PG-liposomes by GPS in Mg-EGTA-GVB was a result of ACP activation mediated by natural antibodies to PG of the IgM type which are present in usual GPS. This conclusion indicated that natural antibodies of the IgM type might play a role with ACP in host defence, especially in C4-deficient guinea-pigs where the classical complement pathway is impaired.

Animals↗
PubMed1983

Coronary reocclusion after selective administration of streptokinase.

Intracoronary streptokinase was given to 40 patients with acute transmural myocardial infarction. In 34 of the patients (85%), it resulted in reflow or improved flow. Six patients showed no reflow and six reocclusion within 2 hours. No consistent explanation was found for this resistance to therapy. Five other patients developed reocclusion after 6 days to 11 months, when heparin or warfarin anticoagulation had been stopped. Percutaneous angioplasty at the time of streptokinase infusion was performed in seven, with six successes. Bypass surgery was performed after successful streptokinase administration in eight. Follow-up revealed recurrent ischemia in patients successfully treated with streptokinase alone, but not in patients with successful angioplasty or bypass surgery. Long-term coronary patency after thrombolysis may require careful anticoagulation or a procedure that modifies or bypasses the residual stenosis.

Angioplasty, Balloon↗
PubMed1983

[In vivo antibacterial activity of cefoperazone in intraperitoneal infections in mice].

The in vivo antibacterial activity of cefoperazone (CPZ) against systemic infections was studied in comparison with that of cefotiam (CTM) using beta-lactamase non-producing bacteria and producing bacteria. In vitro antibacterial activity of CPZ against Gram-positive bacteria was slightly inferior to that of CTM, but there was no significant difference between their in vivo activities. On the other hand, the therapeutic effect of CPZ against Gram-negative bacteria was nearly parallel to in vitro antibacterial activity and particularly was superior to that of CTM against cephalosporinase (CSase) producing bacteria. The ascitic levels of CPZ in mice infected with CSase producing bacteria were persisted longer, but those of CTM disappeared quickly after administration. This result appeared to reflect on the therapeutic effects of both drugs.

Animals↗
PubMed1983

[In vivo effects of cefoperazone in local infection].

The in vivo antibacterial activity and the penetration into inflammatory tissues of cefoperazone (CPZ) were compared with those of cefotiam (CTM) in local infection systems using mouse subcutaneous abscess and rat granuloma pouch. The serum levels of CPZ in subcutaneous abscess in mice caused by Staphylococcus aureus F-230 (penicillinase producing strain) were lower than that of CTM, but there was no significance between the therapeutic effects of both drugs. The same results were obtained using Staphylococcus aureus F-196 (penicillinase non-producing strain). When infected with Enterobacter cloacae H-27 (cephalosporinase producing strain) in rat granuloma pouch, the exudate levels of CTM were lower than those of CPZ. Judging from these results, it was suggested that CPZ was a useful antibiotic for the treatment of bacterial-inflammatory tissues.

Abscess↗
PubMed1983

Asymmetric (differential) cell division of thymic lymphocytes by means of cytoplasmic polarization: possible biological meanings.

A series of morphological studies at the light- and electron-microscopical levels have led to the conclusion that a significant proportion of immature thymic lymphocytes would undergo asymmetric (differential) cell division: at the telophase of such dividing cells one of two daughter cells retains morphological characteristics very similar to those of its parent cell, whereas the counterpart daughter cell looks much differentiated. Polarization of the cytoplasm is considered to be the mechanism whereby the asymmetry is generated. The phenomenon is observable in both prenatal and postnatal life of all the animal species examined, that is chicken, guinea pig, rat and mouse, meaning that it is a general phenomenon among the animals possessing the thymus. The frequency of asymmetrically-dividing cells is relatively high in large-sized cell fractions (more than 40% of total dividing cells). The conclusions leading from the above-mentioned morphological studies are supported by the cell kinetic studies performed by Metcalf in the mid-1960s. Asymmetric cell division may be primarily involved in the maintenance of immature 'stem cells' while concomitantly producing differentiated cells of smaller sizes. The phenomenon might also play an important role in the differentiation of thymocytes into distinct lineage of thymic lymphocytes such as cortex and medulla lymphocytes. Furthermore, the present findings raises the idea that hematopoietic cells including lymphoid cells would possess, in general, intracellular mechanisms to undergo asymmetric cell division.

Age Factors↗
PubMed1983

[In vitro antibacterial activity of cefoperazone].

The in vitro antibacterial activities of cefoperazone (CPZ) against clinical isolates including various beta-lactamase-producing strains were studied and compared with those of cefotiam (CTM). CPZ had a broad spectrum against Gram-negative and Gram-positive bacteria. Especially, CPZ showed apparently more potent antibacterial activities than CTM against Enterobacter cloacae, Serratia marcescens, and Pseudomonas aeruginosa. However, CPZ was less active than CTM against Staphylococcus aureus and Proteus mirabilis. The stability and affinity of CPZ for various types of beta-lactamase were also studied. CPZ was more resistant to hydrolysis by typical cephalosporinase (CSase) and cefuroximase (CXase) than CTM, but was less stable to penicillinase (PCase). CPZ often showed higher affinity to beta-lactamases than CTM. The study for the inducer-activity revealed that CPZ hardly induced CSase production in E. cloacae and Proteus vulgaris while CTM highly induced in both strains. CPZ was more active against CSase-producers than CTM, especially against strains which inducibly produced the enzyme. It was speculated that this activity was responsible for the superior stability to CSase and low inducer-activity for CSase production.

Bacteria↗
PubMed1983

Steady-state kinetic studies of binding and catalysis by ribonuclease T2: a microenvironmental survey of the active site by using a series of adenosine-3'- and -5'-alkylphosphates.

The effects of a series of adenosine-3'-alkylphosphates, Ap(CH2)n-1CH3 with n = 1-8, on the binding and catalytic activities of RNase T2 were investigated. The inhibition of the RNase T2-catalyzed reaction by a series of adenosine-5'-alkylphosphates, CH3(CH2)n-1pA with n = 1-7, was also studied. Multiple regression analyses of the observed kinetic constants were carried out to determine the contribution of polar and hydrophobic effects to kcat, kcat/Kmi, and cosubstrate and inhibitor bindings (Kmi and Ki). The data show that the pKmi for Ap(CH2)n-1CH3 increases uniformly with n up to n = 4, then remains constant. By contrast pKi for CH3(CH2)n-1pA is independent of n. The data for log kcat correlated well with polar and hydrophobic variables. On the other hand, log kcat/Kmi is independent of a hydrophobic effect, and the data were fitted by a single polar variable equation. The contribution of hydrophobic regions at or near the active site of RNase T2 is discussed. The present results also offer evidence for the existence of an isomerization step of the first formed enzyme-substrate complex.

Adenine Nucleotides↗
PubMed1983

Effect of Bordetella pertussis leukocytosis (lymphocytosis)-promoting factor (LPF) on the physical lymphoepithelial-cell association studied with the use of an in vitro model of mouse thymus.

The effect of highly purified leukocytosis (lymphocytosis)-promoting factor (LPF) of Bordetella pertussis on physical lymphocyte and reticuloepithelial (RE) cell association was studied in an in vitro thymus model. First, a simplified in vitro system to assess the lympho-RE-cell association was developed. A completely confluent layer of thymic RE cells was formed by cultivating trypsinized thymus cell suspensions from 2- to 7-day-old mice. When thymic lymphoid cells were seeded on this cell layer and cultivated overnight, a significant proportion of them were found underneath the RE cell layer. This physical lympho-RE-cell association was quantitated by counting the lymphoid cells underneath the RE cell layers. Second, the effect of LPF on this physical lympho-RE-cell association phenomenon was investigated. Addition of LPF to the culture markedly inhibited the formation of the lympho-RE-cell complex; that is, it inhibited the infiltration of lymphoid cells under the RE cell layer. LPF rendered a nearly maximal level of inhibitory effect at a dose of 0.1 ng/ml. Furthermore, LPF enhanced the liberation of lymphoid cells from preformed lympho-RE-cell complexes. On the other hand, LPF had no direct cytotoxic effect on lymphoid cells at doses below 1 microgram/ml. In order to investigate whether LPF produced the effect by acting on lymphoid cells, RE cells, or both, the following experiments were performed. When lymphoid cells were pretreated with LPF and added to normal RE cell layers, the lympho-RE-cell association was maximally inhibited above the dose of 1 ng/ml. Treatment of these LPF-treated lymphoid cells with anti-LPF antibodies failed to abrogate the effect of LPF. When RE cell layers were similarly pretreated with LPF and were cultivated with normal lymphoid cells, however, much higher doses of LPF, above 100 ng/ml, were required for maximal inhibition. Furthermore, treatment of these LPF-treated RE cells with anti-LPF antibodies abrogated the effect of LPF. Therefore, the apparent effect of LPF on RE cells was considered to be due to the carry-over by RE cells of LPF, which should directly act on lymphoid cells at extremely low doses. On the basis of these results, it was concluded that LPF acted directly on lymphoid cells without mediation of RE cells. These in vitro results appear to parallel the effects of LPF in vivo, where it induces a depletion of cells in the thymus. The model may be useful to study this phenomenon and the concomitant accumulation of blood lymphocytes.

Animals↗
PubMed1983

Membrane sialoglycolipids regulate the activation of alternative complement pathway by liposomes containing trinitrophenylaminocaproyldipalmitoylphosphatidylethaolamine.

We found that liposomes associated with trinitrophenylaminocaproyldipalmitoylphosphatidylethanolamine (TNP-Cap-DDPE) activate the alternative complement pathway (ACP) of guinea-pig. The complement-activating capacity (CAC) of liposomes with TNP-Cap-DPPE (TNP-Cap-liposomes) was found to be inhibited by the insertion of sialoglycolipids such as GM3 onto the membrane. However, neutral glycolipids tested had no inhibitory effect on the CAC of the TNP-Cap-liposomes. The minimum amount of sialoglycolipids required for the inhibition of the ACP-activating capacity of TNP-Cap-liposomes was 0.01 or less in molar ratio to dimyristoylphosphatidylcholine in the liposomes. Since the insertion of charged amphiphiles did not affect the status of TNP-Cap-liposomes containing glycolipids with respect to their ACP-activating capacity, the surface potential caused by sialoglycolipids was disregarded as being the factor responsible for restriction of the complement-activating effect. For the inhibitory effect to be manifested, it was demonstrated that the presence of GM3 was required on the same liposome membrane as where the TNP-Cap-triggered ACP activation is taking place. Therefore, sialoglycolipids may inhibit ACP activation by reacting directly on certain nascently activated complement proteins. However, insertion of GM3 could not inhibit liposome lysis via the classical complement pathway. Furthermore, the presence of antibody reaction significantly reduced the inhibitory capacity of GM3 indicating that natural antibody may be responsible for discriminating between self and heterologous surfaces, thus cancelling the glycolipid-mediated restriction of ACP activation in the case of heterologous cell surface, bringing about lysis by the cancellation of the glycolipid-mediated restriction of ACP activation on heterologous cell surfaces.

Animals↗