Left atrial free-floating thrombus with multiple systemic emboli in orthotopic heart transplantation.
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Echocardiography↗
Biomedical subjects
F Alonso
Publications and source records attributed to F Alonso.
Analysis of T lymphocyte subsets proliferating in response to infective and UV-inactivated African swine fever viruses.
The proliferative response to infective and UV-inactivated African swine fever virus was analyzed in cells from pigs surviving an experimental infection with attenuated virus. All the pigs showed strong dose-dependent proliferative responses to both infective and UV-inactivated virus. This response was also observed when nitrocellulose-bound solubilized virus proteins were used in the assay. Heterologous isolates also induced proliferation, however it was significantly lower than that induced by the isolate used to infect the animals. The response to infective virus was blocked equally by anti-CD4 and anti-CD8 monoclonal antibodies (mAb); the response to UV-inactivated virus was almost abolished by anti-CD4 and 60% inhibited by anti-CD8 mAb. FACS analysis of 28-day T cell lines derived from peripheral blood mononuclear cells demonstrated the progressive increase of the CD8+ subset when the cells were stimulated with infective virus, whereas the stimulation with UV-inactivated virus induced the increase of both CD4+ and CD8+ subsets. In this case, the sum of CD4+ and CD8+ percentages was higher than the total percentage of T cells, suggesting the presence of cells positive for both CD4+ and CD8+.
African Swine Fever↗
Heterotypic lymphoproliferative response in pigs vaccinated with foot-and-mouth disease virus. Involvement of isolated capsid proteins.
The in vitro viral lymphoproliferative response of pigs vaccinated against foot-and-mouth disease virus (FMDV) has been characterized. Peripheral blood mononuclear cells from immunized animals up to 1 year post-immunization (p.i.) showed a time-dependent FMDV-specific response, as assayed by virus-specific cellular blastogenesis. The optimum viral concentration decreased with time (around 20 weeks p.i.), and the response was faster and weaker. Lymphoproliferation appeared to be mainly due to CD4+ T cells. The response was heterotypic, being induced by all FMDV serotypes tested (C, A and O) after only two vaccinations with FMDV of serotype C (C-S8). Each individual structural protein assessed (VP1, VP2 and VP3) induced proliferation, with VP3 and VP1 being more effective stimulators. In vitro serum neutralization activity and FMDV-specific IgG production were found to be active even at 1 year p.i.
Animals↗
[Thrombocytosis in a Ph1 positive chronic myeloproliferative syndrome. Chronic myeloid leukemia or essential thrombocythemia].
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Aged↗
Inhibition of natural killer activity in porcine mononuclear cells by African swine fever virus.
The coincubation at 37 degrees C for 24 hours of swine peripheral blood mononuclear cells with African swine fever virus inhibited in part the natural killer activity shown by cells incubated without the virus. This inhibition depended on the dose of the virus and on the time that cells were incubated with it. When the virus preparation was fractionated by ultracentrifugation, most of the inhibitory activity was found in the sedimented fraction, where viral particles were present; however, the loss of inhibitory activity in respect to the whole virus preparation indicated that some inhibitory activity was present in the supernatant fraction, probably as factors released by infected cells. Most of the inhibitory activity shown by the sedimented fraction was lost when the virus was inactivated by ultraviolet radiation, indicating an active role of virus infectivity in the inhibition.
African Swine Fever Virus↗
Inhibitory effect of African swine fever virus on lectin-dependent swine lymphocyte proliferation.
The incubation of swine peripheral blood mononuclear cells (PBMC) with African swine fever (ASF) virus preparations strongly inhibited the proliferative response of lymphocytes to PHA and other lectins. The inhibition, which persisted after inactivation of the virus by UV radiation, was dependent upon the dose and the time that virus preparations were present in cultures. When virus preparations were fractionated by ultracentrifugation, the inhibitory activity resulted to be soluble, whereas no activity was found in the sedimented viral fraction. However, the preincubation during 4 days of this sedimented fraction with swine PBMC, before the addition of the mitogen, restored the inhibitory activity. The results obtained suggest that the inhibition is mediated by one or more soluble factors released by swine PBMC after coincubation with ASF virus in a time dependent process. These factors show a molecular weight between 40 and 80 kDa by gel filtration chromatography. The inhibitory activity described in the present paper is an indication of inhibition of lymphocyte function produced by ASF virus which can help to understand how this virus escapes from the host immune system.
African Swine Fever↗
Expression of swine transmissible gastroenteritis virus envelope antigens on the surface of infected cells: epitopes externally exposed.
The peplomer protein (S) and the transmembrane protein (M) of transmissible gastroenteritis virus (TGEV) of swine were identified by iodination and serologically on the surface of infected cells. Of a total of 4 monoclonal antibodies (mAb) directed against four antigenic sites of S protein (Correa et al., 1988), 3 specific for sites A, B and D attached to the plasma membrane of infected cells, as disclosed by indirect immunofluorescence and by complement-mediated cytolysis. Four of the mAbs assayed were specific for the viral protein M and two of them gave plasma membrane immunofluorescence and mediated cytolysis in the presence of complement. The viral nucleoprotein N could not be demonstrated on the surface of infected cells either by iodination or employing 3 mAbs against this protein. Finally, a time course infection experiment demonstrated that S and M proteins were expressed on the surface of infected cells at 4 h after infection, before infective virus was released from infected cells.
Animals↗
[Polycystic nephroma: imaging diagnosis and its pathologic correlation. Apropos of a case].
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Child, Preschool↗
A cytosolic phospholipase in human neutrophils that hydrolyzes arachidonoyl-containing phosphatidylcholine.
In stimulated neutrophils the production of eicosinoids and the lipid mediator, platelet-activating factor, is thought to be initiated by the activation of a phospholipase A2 which cleaves arachidonic acid from choline-containing glycerophospholipids. Accordingly, studies were undertaken in human neutrophils to characterize phospholipase enzymes that can hydrolyze 1-acyl- and 1-alkyl-linked arachidonoyl-containing phosphatidylcholine (PC). Cellular homogenates were incubated with sonicated dispersions of the arachidonoyl-labeled phospholipid substrates and the hydrolysis of radiolabeled arachidonate was measured. The phospholipase activity was cytosolic, optimal at pH 8.0, and calcium dependent. The homogenization conditions used were important in determining the amount of recoverable enzymatic activity. Vigorous sonication and the presence of calcium during homogenization were strongly inhibitory, whereas the presence of EGTA, heparin and proteinase inhibitors during homogenization increased the activity. Competitive experiments with unlabeled substrates suggested that the phospholipase hydrolyzed arachidonic acid equally well from either 1-acyl- or 1-alkyl-linked PC. However, the phospholipase did show specificity for arachidonic acid, compared to oleic or linoleic acids, at the sn-2 position of 1-acyl-linked PC. When neutrophils were first stimulated with the ionophore A23187, the phospholipase activity against 1-O-hexadecyl-2-[3H]arachidonoylglycerophosphocholine (GPC) increased in a time-dependent fashion up to 3.5-fold over the unstimulated level. The activity against 1-palmitoyl-2-[3H]arachidonoyl-GPC also increased after ionophore stimulation but to a lesser extent. The results demonstrate the presence of a cytosolic, activatable phospholipase that may be involved in PC turnover, arachidonic acid release, and platelet-activating factor production in human neutrophils.
Arachidonic Acid↗
Synthesis of platelet-activating factor from human polymorphonuclear leukocytes: regulation and pharmacological approaches.
Human polymorphonuclears release a platelet-activating factor (PAF-acether) when challenged with various stimuli. PAF-acether is a mediator that is synthesized during cell activation in a process in which a phospholipase A2 and an acetyltransferase take part. These enzymes are finely regulated and accordingly PAF-acether release may be modulated. The authors have studied some of the transductory mechanisms which are triggered during cell stimulation and the effect of their pharmacological modulation on PAF-acether release. Theophylline, methylisobutylxanthine and dipyridamole, which block phosphodiesterase of cyclic nucleotides, induce a dose-dependent inhibition of PAF-acether release without affecting phagocytic uptake. Polyamines (dansylcadaverine, rimantadine and amantadine) reduced PAF-acether release and the phagocytic process in an order of potency similar to their ability to inhibit phospholipid methylation and the cholinephosphotransferase pathway. The calmodulin antagonist trifluoperazine induced a dose-dependent inhibition of PAF-acether release and acetyltransferase at concentrations from 10(-4) to 10(-5) M. Hence it appears that modulation of PAF-acether release can be obtained by different pharmacological blockades: phosphodiesterase of cyclic nucleotides, phospholipid metabolism and calcium-calmodulin.
Acetyltransferases↗
The role of calcium ions in the process of acetyltransferase activation during the formation of platelet-activating factor (PAF-acether).
The role of Ca2+ in the activation of the enzyme lyso-(platelet-activating factor): acetyl-CoA acetyltransferase was studied in rat peritoneal macrophages in response to complement-coated zymosan particles and ionophore A23187. By using Ca2+-containing buffers, a threshold concentration of extracellular Ca2+ above 1 microM was found to be necessary to observe the activation of the enzyme in response to zymosan. By contrast, a significant role of intracellular Ca2+ in this process could be ruled out, since the putative intracellular calcium-transport antagonist TMB-8 [8-(NN-diethylamino)octyl-3,4,5-trimethoxybenzoate] did not inhibit the activation of the acetyltransferase induced by zymosan in the presence of extracellular Ca+. The link between acetyltransferase activation and extracellular Ca2+ transport was studied by measuring Ca2+ uptake in response to the stimuli. Zymosan particles induced a rapid increment in cell-associated Ca2+ which correlated well with the extent of acetyltransferase activation (r = 0.91) and with the release of platelet-activating factor (r = 0.95) in response to different doses of zymosan. Cellular Ca2+ efflux in response to zymosan particles was also measured and found to be increased, as compared with controls, when the activation of the acetyltransferase declined. In short, the data suggest that the entry of extracellular Ca2+ into the cell is a crucial event in the activation of acetyltransferase and, thereby, in the formation of platelet-activating factor in rat peritoneal macrophages.
Acetyl-CoA C-Acetyltransferase↗
Hypomelanosis of Ito. Case report with involvement of the central nervous system and review of the literature.
A case of hypomelanosis of Ito in a ten-year-old black boy with mental retardation, epilepsy and abnormalities of the white matter of the cerebral hemispheres revealed by a computerized tomography is presented. This is the 41st reported case on this disease, a number of which have shown neurological signs. A review of the literature with emphasis on the neurological manifestations is performed.
Central Nervous System Diseases↗
Biosynthesis of J-chain in human lymphoid cells producing immunoglobulins of various isotypes.
The relationship between synthesis, secretion, and subcellular localization of J-chain, IgM, IgA, and IgG was investigated in cultures of PWM-stimulated human PBL and in lymphoblastoid cell lines. Cells were examined for surface, cytoplasmic, and secreted immunoglobulins (Igs) and J-chain by immunofluorescence and radioimmunoassay (RIA). By these techniques, J-chain was detected in cells that produce polymeric or monomeric Igs. In PWM-stimulated PBL the synthesis of J-chain paralleled the production of Igs. In both PWM-stimulated (for 2 days) and unstimulated PBL, equal proportions of free and disulfide-linked J-chain were found. Increased amounts of intracellular J-chain were produced at later stages in PWM-stimulated PBL and J-chain occurred mostly in a free form. In tissue culture fluids, J-chain was not secreted in a free form but was always disulfide-linked to polymeric Igs. In lymphoblastoid cell lines, J-chain was present in a disulfide-linked form in IgM and IGA producers, but in IgG cells and in an IgM cell line (DAUDI) that did not secrete IgM but expressed it on the cell membrane, intracellular J-chain was present in free form. Although various proportions of polymeric and monomeric IgA were seen in culture fluids from IgA-secreting cell lines, intracellular IgA occurred mostly in a monomeric form. Further studies revealed that the ability to produce polymers was not equally distributed among all cells and might vary according to their content of J-chain and stage of maturation. Subcellular fractionation and subsequent analyses for J-chain and Ig in PWM-stimulated PBL and in IgM or IgG-producing cell lines revealed that these proteins were associated with fractions that contained ribosomes, cell sap, and low molecular weight RNA. In lysates of IgG and J-chain producing cells grown in the presence of 3H-labeled amino acids, intracellular J-chain was not disulfide-linked to IgG.
Cell Line↗
Platelet-activating factor: an effector substance of the vasopermeability changes induced by the infusion of immune aggregates in the mouse.
The effect of intravenous infusion of heat-aggregated IgG on vascular permeability was studied by using 51Cr-labelled homologous red blood cells in mice. Simultaneously, the recovery of platelet-activating factor (PAF) from the mononuclear phagocytic system (MPS) was attempted. Whereas PAF was found only in trace amounts in the liver of control animals, the infusion of aggregates induced the release of PAF from liver and spleen in a time- and dose-dependent manner. A possible link between PAF release and permeability is sustained on the following basis. PAF release precedes permeability changes and both show a parallel dose-response pattern plateauing for doses higher than 1 mg. Further, depletion of mononuclear phagocytes by total irradiation with 700 rads, or pharmacological blockade of phospholipases by prior treatment with quinacrine, induced abrogation of permeability changes and PAF release from spleens, together with an 80% reduction of the amount of PAF obtained from livers. These data suggest the following conclusions: 1) PAF release may occur in vivo when the MPS is stimulated by phagocytosable material; 2) PAF seems to be an effector substance of the permeability changes which occur during the administration of immune aggregates.
Animals↗
Presence in normal human urine of a hypotensive and platelet-activating phospholipid.
Urine from normotensive volunteers and patients with systemic lupus erythematosus glomerulonephropathy was sequentially concentrated by negative-pressure ultrafiltration, dialyzed against distilled water, and extracted into the chloroform phase of a mixture of organic solvents(chloroform:methanol:water, 1:1:0.9 vol/vol). The lipid fraction was further purified by thin-layer chromatography on silica gel plates using neutral, acidic, and basic mixtures of organic solvents and it was then tested for its ability to induce the release of [3H]serotonin from rabbit platelets. All of the samples contained a platelet-activating moiety similar to a synthetic platelet-activating factor (PAF-acether) on the basis of its chromatographic behavior, resistance to the pretreatment of platelets by 10(-6) M indomethacin, and loss of activity by alkaline methanolysis or treatment by phospholipases A2, C, and D. Cross-densensitization experiments between synthetic PAF-acether and the urine factor showed that both compounds act on platelets through the activation of the same putative receptor. Further, the urine factor induced hypotension when intra-arterially injected in normotensive rats, and this activity was also abrogated by alkaline methanolysis. In summary, these data provide evidence of the presence in normal human urine and, probably, of the release by the kidney of a lipid factor with platelet-activating and hypotensive activity whose general structure seems to be alkyl-acyl-glyceryl-phosphorylcholine and, therefore, is similar to the structure of the inflammatory mediator PAF-acether and the antihypertensive polar renomedullary lipid.
Animals↗
Phospholipid turnover during phagocytosis in human polymorphonuclear leucocytes.
We have previously observed that the phagocytosis of zymosan particles coated with complement by human polymorphonuclear leucocytes is accompanied by a time- and dose-dependent inhibition of phosphatidylcholine synthesis by transmethylation [García Gil, Alonso, Sánchez Crespo & Mato (1981) Biochem. Biophys. Res. Commun.101, 740-748]. The present studies show that phosphatidylcholine synthesis by a cholinephosphotransferase reaction is enhanced, up to 3-fold, during phagocytosis by polymorphonuclear cells. This effect was tested by both measuring the incorporation of radioactivity into phosphatidylcholine in cells labelled with [Me-(14)C]choline, and by assaying the activity of CDP-choline:diacylglycerol cholinephosphotransferase. The time course of CDP-choline:diacylglycerol cholinephosphotransferase activation by zymosan mirrors the inhibition of phospholipid methyltransferase activity previously reported. The extent of incorporation of radioactivity into phosphatidylcholine induced by various doses of zymosan correlates with the physiological response of the cells to this stimulus. This effect was specific for phosphatidylcholine, and phosphatidyl-ethanolamine turnover was not affected by zymosan. The purpose of this enhanced phosphatidylcholine synthesis is not to provide phospholipid molecules rich in arachidonic acid. The present studies show that about 80% of the arachidonic acid generated in response to zymosan derives from phosphatidylinositol. A transient accumulation of arachidonoyldiacylglycerol has also been observed, which indicates that a phospholipase C is responsible, at least in part, for the generation of arachidonic acid. Finally, isobutylmethylxanthine and quinacrine, inhibitors of phosphatidylinositol turnover, inhibit both arachidonic acid generation and phagocytosis, indicating a function for this pathway during this process.
1-Methyl-3-isobutylxanthine↗
Activation of 1-alkyl-2-lysoglycero-3-phosphocholine. Acetyl-CoA transferase during phagocytosis in human polymorphonuclear leukocytes.
1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine can be synthesized either by acetylation of 1-alkyl-2-lyso-sn-glycero-3-phosphocholine or by transcholination of 1-alkyl-2-acetyl-sn-glycerol. Addition of opsonized zymosan to isolated human polymorphonuclear leukocytes induces a fast, transient, up to 10-fold activation of the acetyltransferase reaction without affecting the cholinephosphotransferase pathway. Based on the following results, we propose that the generation of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine by human polymorphonuclear leukocytes during phagocytosis is mediated by a stimulation of the acetyltransferase reaction: 1) the time course of acetyltransferase activation agrees with it being the enzyme responsible for the synthesis of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine; and 2) a close correlation exists (r = 0.91) between the generation of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine in response to various doses of zymosan and the magnitude of acetyltransferase activation.
Acetyltransferases↗
Modulatory role of cyclic AMP in the release of platelet-activating factor from human polymorphonuclear leucocytes.
Zymosan coated with complement (Zc) was observed to induce a transient elevation of the intracellular cyclic AMP in human polymorphonuclear cells: a two- to three-fold increase was observed within 1 min after stimulation and approached prestimulation levels by 2 min incubation. These changes in cyclic AMP were not associated with significant changes in cyclic GMP levels. Zymosan caused the release of PAF and beta-glucuronidase and particle uptake, which was initiated about 5 min after stimulation. These results suggest that the transient increase in cyclic AMP content might regulate an early event during mediator release. In an attempt to study further the significance of this rise in cyclic AMP, cells were preincubated with various phosphodiesterase inhibitors. Preincubation of the cells with methylisobutylxanthine (MIX, 10(-6) M to 5 X 10(-5) M), theophylline (3 X 10(-5) to 3 X 10(-3) M) or dipyridamole (10(-6) M to 10(-4) M) enhanced the increase in cyclic AMP levels, but resulted in dose-dependent inhibition of Zc-induced mediator release. Particle uptake and beta-glucuronidase release were less sensitive than PAF release to phosphodiesterase inhibitors, which argues in favour of the independence of both phenomena. Synergistic experiments with MIX and cyclic AMP indicate that the effect of this drug is through its action on cyclic AMP levels. These results suggest that while Zc-induced cyclic AMP elevation might occur in an intracellular place critical to its effect; phosphodiesterase inhibitors may elevate cyclic AMP levels throughout the cell and therefore inhibit the biological response.
Blood Coagulation Factors↗