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Biomedical subjects

A Canals

Publications and source records attributed to A Canals.

35 records · Page 2Linked to original sources
PubMed1997

Cloning and expression of bovine interleukin-15: analysis and modulation of transcription by exogenous stimulation.

The bovine interleukin-15 (IL-15) sequence was cloned from abomasal lymph node mRNA by enzymatic amplification of cDNA using human primers proximal to and including the translation start and stop sites. The open reading frame is 486 base pairs in length, and the proposed protein sequence shows 78.4% and 73.5% similarity with that predicted for the human and mouse sequences, respectively. Expressed and purified recombinant bovine IL-15 in the absence of the 48-amino acid leader sequence stimulated the proliferation of bovine lymphoblast cells at least 12-fold over background at maximum concentration levels. Competitive reverse transcriptase-polymerase chain reaction analysis showed constitutive levels of IL-15 mRNA within a broad range of tissues and cell types. Lipopolysaccharide addition to adherent lymph node populations caused moderate increases in IL-15 transcription, whereas the addition of phorbol 12-myristate 13-acetate and calcium ionophore failed to induce gene expression for this cytokine. Transcription of IL-15 was also downregulated in the presence of low concentrations of human recombinant interleukin-2.

Amino Acid Sequence↗
PubMed1997

Quantification of cytokine gene expression in lamina propria lymphocytes of cattle following infection with Ostertagia ostertagi.

Changes in cell surface markers and cytokine transcription were analyzed in lamina propria lymphocytes from control animals (noninfected calves) and calves after a single high but nonprotective primary infection with Ostertagia ostertagi. Flow cytometry of cells recovered from the lamina propria showed an increase in the percentages of IgM+, WC1+, and IL-2R+-bearing cells 10 days after infection; however, 2 mo after infection, cell staining was comparable to preinfection levels. Transcription levels of interleukins IL-2, IL-4, IL-10, and interferon (IFN)-gamma mRNA were measured using a competitive reverse transcription-polymerase chain reaction. Results indicated elevated levels of IL-4 and IFN-gamma in the infected animals at 10 days and at 60 days after infection. Transcription of IL-10 also increased; however, this change was not observed until 60 days postinfection.

Animals↗
PubMed1996

Automatic flow-injection system for the determination of heavy metals in sewage sludge by microwave digestion and detection by inductively coupled plasma-atomic emission spectrometry (MW-ICP/AES).

Results are shown obtained in the optimization of an automatic flow injection system that combines microwave digestion with atomic spectrometric detection (FAAS, ICP/AES) for the determination of heavy metals in sewage sludge. Digestion is performed by preparing a suspension of the sample in 1.5 mol/l HNO(3) and making it flow through a PTFE capillary tube placed inside a conventional microwave oven. The effects of the length and inner diameter of the capillary tube, as well as that of the pumping rate, have been studied in order to find the experimental conditions that allow a quantitative elemental recovery in the shortest period of time possible. The optimization study was carried out on a certified sample (BCR No. 146), and the elements determined were Zn, Cu, Pb, Cd, Ni and Cr. The experimental data (percent recovery vs. digestion time) have been fitted to a mathematical model in order to quantify the influence of each of the variables studied. The optimized procedure (MW-ICP/AES) has been applied to one ordinary and one certified sewage sludge sample. In comparison with the conventional methods of sewage sludge analysis, the one proposed is less time consuming, while being equally precise and accurate.

Journal Article↗
PubMed1995

Enzymatic amplification and molecular cloning of cDNA encoding the small and large subunits of bovine interleukin 12.

cDNA generated from stimulated abomasal lymph node cells was used to amplify and clone the 35 kDa and 40 kDa subunits of bovine interleukin 12 (IL-12) using primers derived from semi-conserved regions between human and mouse IL-12 sequences. The deduced amino acid sequence of the 40 kDa subunit demonstrated 84.4% and 67.6% homology with human and mouse sequences, respectively. The deduced sequence of the 35 kDa subunit exhibited comparable similarities to the human 35 kDa subunit (82.2%) but differed significantly (58.6%) from mouse-derived sequences.

Amino Acid Sequence↗
PubMed1995

Inhibition of IL-2R and SLA class II expression on stimulated lymphocytes by a suppressor activity found in homogenates of African swine fever virus infected cultures.

Virus free supernatants (VFS) obtained by ultracentrifugation of homogenates of African swine fever (ASF) virus infected cultures inhibited the proliferative response and the expression in peripheral blood mononuclear cells of two activation molecules, the IL-2 receptor (IL-2R) and the swine MHC class II antigens (SLA II), induced by several stimuli (lectins, PMA plus the calcium ionophore A23187 or specific antigen). This inhibition was time dependent: no effect was seen on IL-2R expression when VFS was added after 48 h, when the expression of this molecule reached its maximum. However at this time the proliferative response was still inhibited. The presence of VFS in the cultures was necessary to inhibit both the IL-2R expression and the proliferation of cells. In these conditions the addition of exogenous IL-2 to the cultures failed to restore the IL-2R expression and the proliferation shown by control stimulated cells. Furthermore, the IL-2 activity found in supernatants from cell cultures stimulated with Con A in the presence of VFS was even higher than in cultures stimulated without VFS. The inhibition observed suggests an important impairment of host immunocompetence in ASF infected swine.

African Swine Fever Virus↗
PubMed1994

Summary of workshop findings for porcine T-lymphocyte antigens.

Fifty-four mAb preselected in the first round of the first porcine CD workshop for their possible reactivity with T-lymphocyte specific antigens and/or activation antigens were further analysed in a second round. PBMC, thymocytes and nylon-wool purified T lymphocytes derived from peripheral blood, mesenteric lymph nodes and spleen served as target cells for flow cytometric analyses. For the classification of activation antigens several experiments were performed with activated, mitogen-stimulated T lymphocytes and long-term T-lymphocyte cultures. Out of the 54 mAb, 35 mAb could be distributed to six different CD clusters and two swine workshop clusters (SWC). Five mAb could be distributed to the porcine CD2, four mAb to the CD4. Six mAb seemed to recognize the porcine CD5 and two mAb the porcine CD6 analogue. Six mAb were directed against the porcine CD8, whereas two different epitopes could be defined. One mAb was directed against the porcine CD25 analogue. Nine mAb could be clustered to the SWC1, defining an antigen on T lymphocytes and cells of the myeloic linage. Two mAb with high T-cell specificity were clustered to the SWC2.

Animals↗
PubMed1994

Analysis of monoclonal antibodies reactive with the porcine CD2 antigen.

As result of the First International Swine CD Workshop, six monoclonal antibodies (mAbs) (numbers 014, 023, 024, 057, 128, and 130) clustered closely to the internal standard anti-porcine CD2 mAb, MSA4. Despite the close clustering, the cluster was split into two subgroups. To further characterize the relationship between these mAbs, they were used in flow cytometry to inhibit binding of MSA4 to porcine lymphocytes. mAbs 014 (1038-8-31), 023 (MAC83), 024 (MAC80), 057 (PG168), and 128 (MSA4) completely inhibited the binding of MSA4, mAb 130 (MSA2) failed to inhibit MSA4 binding. On dual parameter flow cytometry comparing MSA2 with MSA4, all MSA2+ cells were MSA4+, two thirds of the MSA4+ cells were MSA2-. We conclude that five of the mAbs bind to the same or a closely related epitope on porcine lymphocytes. mAb 130 appears to have aberrantly clustered with the CD2 group of mAb.

Animals↗
PubMed1994

Analysis of monoclonal antibodies reactive with the porcine CD4 antigen.

As result of the First International Swine CD Workshop, four monoclonal antibodies (mAb) (#002, 054, 118, and 127) clustered closely to the internal standard anti-porcine CD4 mAb, 74-12-4. To further characterize the relationship between these mAb, they were used in flow cytometry to inhibit binding of 74-12-4 to porcine lymphocytes. mAb #002 (74-12-4) and #054 (PT90) completely inhibited, while mAb #127 (10.2H2) and #118 (b38c6) partially inhibited (57% and 77% respectively), the binding of 74-12-4. Furthermore, none of the mAbs bound to a 74-12-4 negative strain of pigs. We conclude that the four mAb bind to the same, or a closely related, epitope on porcine lymphocytes.

Animals↗
PubMed1994

Analyses of monoclonal antibodies reactive with porcine CD5.

Among all monoclonal antibodies (mAbs) analyzed in the first porcine CD workshop, six mAbs showed reactivity to the porcine CD5 antigen (workshop mAbs 067, 068, 069, 070, 071 and 119). Because of lack of immunoprecipitation studies for five (067, 068, 069, 070 and 071) out of the six mAbs, only one mAb (119) could be definitely characterized as mAb against the monomeric 63 kDa porcine CD5 antigen. The five other mAbs included in this cluster are characterized by an identical labelling pattern in FCM and competition of the CD5 epitope recognized by mAb 119. These mAbs were allocated to the wCD5 subcluster.

Animals↗
PubMed1994

Analyses of monoclonal antibodies reactive with porcine CD6.

Amongst the monoclonal antibodies (mAbs) submitted to the first porcine CD workshop, two mAbs (workshop numbers 055 and 120) could be identified to recognize the porcine CD6 analogue. Both mAbs seemed to be highly T-cell specific and showed neither reactivity with cells of the myeloic lineage nor with B lymphocytes. The observed molecular mass of the antigen precipitated by mAb 120 of 110 kDa confirmed this classification. Without molecular analyses of the antigen recognized by mAb 055, but similar staining pattern in FCM compared with 120, mAb 055 was allocated to the wCD6 subcluster.

Animals↗
PubMed1994

Analyses of mAb reactive with porcine CD8.

Among all mAb submitted to the first porcine CD workshop, based on FCM analyses six mAb could be identified to recognize the porcine CD8 analogue (workshop Nos. 004, 051, 052, 053, 108 and 109). In immunoprecipitation studies three mAb (Nos. 004, 108 and 109) recognized an antigen with an apparent molecular mass of about 35 kDa under reducing conditions and about 70 kDa under non-reducing conditions. The molecular masses of the antigens recognized by the three other mAb (Nos. 051, 052 and 053) are still unknown. Epitope analyses performed by blocking experiments led to the determination of two CD8 epitopes: CD8a and CD8b. CD8a is recognized by mAb Nos. 004, 051 and 052, and CD8b by Nos. 053, 108 and 109.

Animals↗
PubMed1994

Analysis of mAb reactive with the porcine SWC1.

Among 54 mAb determined to be reactive with porcine T lymphocytes and/or activation antigens, eight mAb (workshop Nos. 005, 031, 080, 091, 092, 093, 094 and 110) derived from different laboratories grouped together in the T11 cluster and were ordered into the SWC1. One mAb (No. 111) which belong also to this group was lost during the workshop. The SWC1 antigen is a molecule expressed on the majority of leukocytes, resting T lymphocytes, monocytes and granulocytes, but not on B lymphocytes. On T lymphocytes it is down-regulated after activation. The molecular mass of the antigen is unknown. Epitope analyses revealed that seven out of the nine mAb recognized similar epitopes on the SWC1 molecule.

Animals↗
PubMed1992

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↗
PubMed1990

Ostertagia ostertagi: isolation and partial characterization of somatic and metabolic antigens.

One metabolic (ES) and two somatic extracts (AS and MS) were prepared from Ostertagia ostertagi. Partial characterization of the three preparations was accomplished by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot techniques. In immunoblots, AS showed a low number of bands that reacted weakly with sera collected from infected calves. MS reacted strongly with the homologous sera, and a sharp group of bands appeared from 12 to 14 kDa, increasing in intensity as the infection progressed. ES showed a group of strongly immunogenic bands in the range of 16-22 kDa. The three preparations were also tested for reactivity with specific anti-Ostertagia antibodies in an enzyme-linked immunosorbant assay (ELISA). The ELISA results showed that all three worm extracts contained antigen epitopes recognized by circulating antibody in sera taken from O. ostertagi-infected calves. The strongest response was seen when antibodies of the IgG1 isotype were reacted with MS and ES. When sera taken from O. radiatum-infected calves were used both somatic extracts showed high levels of cross-reactivity.

Animals↗
PubMed1990

Evaluation of an enzyme-linked immunosorbent assay to detect specific antibodies in pigs infested with the tick Ornithodoros erraticus (Argasidae).

Ornithodoros erraticus is known to transmit the virus that causes the highly contagious disease, African Swine Fever, in Spain. As part of the disease eradication campaign, an ELISA test to detect specific antibodies against the tick was developed. The ELISA, using salivary gland preparations as an antigen, showed high sensitivity and was able to detect as few as 10 adult ticks. The specific antibodies were detected in the sera 6 weeks after the primary infestation and strongly increased after the challenge. The utility of this test under field conditions was also tested.

Animals↗
PubMed1989

Induction of protective immunity in calves immunized with adult Oesophagostomum radiatum somatic antigens.

Oesophagostomum radiatum, the nodular worm of cattle, is a severe pathogen in previously uninfected calves. However, cattle develop a strong protective immune response upon exposure to the parasite. In order to evaluate whether soluble parasite antigens could induce protective immunity, a soluble fraction was obtained from disrupted adult worms, and this fraction was used to vaccinate calves. The vaccination protocol involved two immunizations. The first was administered intramuscularly with complete Freund's adjuvant, the second was given intraperitoneally with antigen plus alum. This immunization reduced the number of worms developing from a subsequent challenge infection by 85% and also reduced clinical signs associated with infection with adult worms. However, vaccination resulted in decreased weight gains during the larval phase of the infection. Analysis of the immune response generated in the vaccinated calves indicated that protection from infection was significantly correlated with the levels of: (1) circulating parasite-specific IgG2 antibody; (2) cellular immune reactivity as determined in a conventional parasite-specific lymphocyte proliferation assay. Serum anti-O. radiatum IgG2 antibodies from vaccinated calves were used in immunoblots to identify the major immunogens. There were five major immunogens with molecular weights ranging from 70 to 150 kDa. Fractions separated by high-pressure liquid chromatography contained immunogens that were used to immunize calves. Vaccination with these fractions was found to impart the same level of protective immunity and induced similar IgG2 antibody and cellular immune responses as the crude whole worm extract even with 100-fold less protein.

Animals↗