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O Vainio

Publications and source records attributed to O Vainio.

At least 73 records · Page 4Linked to original sources
PubMed1992

Sympatho-adrenal activity and the clinical sedative effect of detomidine in horses.

Thirty-nine horses were given detomidine 10 micrograms/kg bodyweight (bwt) intravenously (iv) and six horses were given a corresponding volume of saline solution before minor procedures. Venous blood samples were collected for catecholamine and cortisol determination immediately before the detomidine or saline injection and 20 mins after it. The behaviour of the horse at the time of detomidine injection and the extent of sedation were evaluated. Plasma adrenaline, noradrenaline and the catecholamine metabolites, 3,4-dihydroxyphenylglycol (DHPG) and 3,4-dihydroxyphenylacetic acid (DOPAC), and cortisol concentrations decreased significantly after administration of detomidine, but they remained unchanged in the control group. A high plasma adrenaline concentration before detomidine injection, indicative of a high level of stress, seemed to correspond with a reduced sedative effect of detomidine. The extent of sedation also was related to the concentrations of adrenaline, noradrenaline and DHPG in plasma after the detomidine injection. The reductions in the plasma catecholamine concentrations may have been caused, in part, by decreased secretion of catecholamines due to the sedative effects of detomidine; but detomidine also influences the plasma catecholamine concentrations by reducing directly sympatho-adrenal activity.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Characterization of the putative avian CD2 homologue.

We describe two mouse mAb recognizing the putative chicken homologue of mammalian CD2 Ag and provide evidence for both structural and functional conservation between the avian and mammalian CD2 molecules. The antibodies were T cell-specific and immunoprecipitated a single diffuse band of Mr 40,000 from lysates of surface-labeled chicken thymocytes and peripheral T cells. Removal of N-linked carbohydrate with endo-beta-N-acetylglucosaminidase F revealed the core protein size of Mr 25,000. A rabbit antiserum raised against a synthetic peptide (CD2-300), composed of 18 amino acid residues of the conserved cytoplasmic domain of human, mouse, and rat CD2, precipitated an Ag similar to chicken CD2. Sequential precipitation with CD2-300 antiserum indicated the conservation of an avian and mammalian CD2 epitope. CD2 expression on thymocytes starts at day 11 of embryonic development, and, during subsequent development, thymic gamma delta cells are all CD2+, whereas most peripheral gamma delta-T cells lack CD2. Functional conservation between the chicken and mammalian CD2 molecules was demonstrated by the induction of DNA synthesis in chicken thymocytes and peripheral T cells with the combination of anti-CD2 mAb and PMA.

Animals↗
PubMed1991

Early separation of B and T lymphocyte precursors in chick embryo.

Embryonic chimeras were used to demonstrate an early separation of chicken T and B cell precursors. Genetically polymorphic cell surface antigens, Bu-1 and Ov, which are expressed on cells of the B and T lineage, respectively, are useful markers in adoptive cell transfer studies. Allelic products Bu-1a and Bu-1b can be detected with monoclonal antibodies (mAbs) L22 and 11G2, respectively, and the Ov antigen with mAb 11A9. Chimeric chickens were constructed by reconstituting irradiated 14-d Ov- H.B19 embryos with the sorted Bu-1+ or Bu-1- fractions of spleen cells from age-matched H.B19 Ov+ embryos. Chimeras were analyzed, 3-4 wk after hatching, for the presence of Ov+ cells in the bursa, thymus, spleen, and peripheral blood lymphocytes. T cell precursors giving rise to thymocytes and peripheral T cells were present only in the Bu-1-, but not in the Bu-1+, fraction. We previously demonstrated that, in contrast, all B cell precursors in spleen from 14-d embryos are exclusively present in the Bu-1+ fraction. We also analyzed the immunoglobulin light chain gene rearrangement in these populations by polymerase chain reaction. We show here that VJ recombination occurs in the Bu-1+, but not in the Bu-1-, fraction of spleen. These data demonstrate an early commitment to the B cell lineage, which occurs before the colonization of the bursa of Fabricius. Segregation of B cell precursors from the other hemopoietic precursors, and consequently separation of T and B cell precursors, occurs before the colonization of the primary lymphoid organs.

Alleles↗
PubMed1991

Chicken major histocompatibility complex-encoded B-G antigens are found on many cell types that are important for the immune system.

B-G antigens are a polymorphic multigene family of cell surface molecules encoded by the chicken major histocompatibility complex (MHC). They have previously been described only on cells of the erythroid lineage. By using flow cytometry, section staining, and immunoprecipitation with monoclonal antibodies and rabbit antisera to B-G molecules and by using Northern blots with B-G cDNA clones, we demonstrate here that B-G molecules and RNA are present in many other cell types: thrombocytes, peripheral B and T lymphocytes, bursal B cells and thymocytes, and stromal cells in the bursa, thymus, and caecal tonsil of the intestine. The reactions also identify at least one polymorphic B-G determinant encoded by the B-F/B-L region of the chicken MHC. The serology and tissue distribution of B-G molecules are as complex as those of mammalian MHC class I and class II molecules. These facts, taken with certain functional data, lead us to suggest that B-G molecules have an important role in the selection of B cells in the chicken bursa.

Animals↗
PubMed1991

Chicken major histocompatibility complex congenic lines differ in the percentages of lymphocytes bearing CD4 and CD8 antigens.

In the experiments to be described two congenic inbred lines CB and CC and two recombinant lines CB.R1 and CC.R1 were used. All four lines differ only in regard to the major histocompatibility complex (MHC). To determine the percentage distributions of the two cell subsets in peripheral blood lymphocytes (PBL) in these lines, monoclonal antibodies to these two antigens were used. By FACScan there were more CD4+PBL in CB and CB.R1 lines (share B-F/B-L region, controlling class I/class II antigens with line CB) than CC and CC.R1, while the reverse was true with CD8+ subsets. There were more CD8+ PBL in the CC and CC.R1 lines and less in CB and CB.R1 lines. The ratio of CD4+ to CD8+ in CB chickens was 3.4 +/- 0.2 and in CC chickens 1.6 +/- 0.1.

Animals↗
PubMed1991

Detomidine reduces the plasma catecholamine, but not cortisol concentrations in horses.

Single doses of the alpha 2-adrenergic sedative-analgesic drug, detomidine (10 micrograms/kg, n = 7; 20 micrograms/kg, n = 9), were administered IV to adult horses. Plasma concentrations of adrenaline, noradrenaline, the catecholamine metabolites 3,4-dihydroxyphenylglycol (DHPG) and 3,4-dihydroxyphenylacetic acid (DOPAC), and cortisol were determined before the medication and 30 minutes after it. The plasma concentrations of noradrenaline and the catecholamine metabolites decreased significantly after administration of both 10 micrograms/kg and 20 micrograms/kg of detomidine. Plasma adrenaline level had a tendency to decrease, but plasma cortisol levels were not influenced. The findings suggest a reduction in sympatho-adrenal activity in horses treated with detomidine.

Animals↗
PubMed1991

Peptidergic innervation of the Bursa Fabricii: interrelation with T-lymphocyte subsets.

In birds, B-lymphocytes mature in a special immune organ, the Bursa Fabricii. This organ thus offers unique possibilities for the study of the microenvironment of B-lymphocyte differentiation. We previously reported tachykinin-, vasoactive intestinal peptide-, calcitonin gene-related peptide- and galanin-immunoreactive (ir) fibres in the chicken bursa. As judged from light microscopic studies, each of the peptides was found in fibres contacting B-lymphocytes. Vasoactive intestinal peptide-ir fibres contacted macrophages. Now, we demonstrate neuropeptide Y, indicating the sympathetic nervous system, in fibres associated with arteries, not entering the follicles. CD4- and CD8-positive T-lymphocytes were dispersed in bursal follicles and the connective tissue, most densely in subepithelial regions. We could not find close apposition of fibres with either T-cell subset. We conclude that the potential neuro-immune axis in the Bursa Fabricii may represent a neuro-B-cell-link with only indirect participation of T-lymphocytes. The sympathetic input may influence the bursal microenvironment primarily by regulating the blood supply.

Animals↗
PubMed1990

Reversal of medetomidine-induced cardiovascular and respiratory changes with atipamezole in dogs.

The effects of atipamezole, an alpha 2-antagonist, on six medetomidine-sedated laboratory beagles were studied in a randomised complete block design. The dogs were sedated with medetomidine (20, 40 or 80 micrograms/kg intramuscularly) and five- and 10-fold larger doses of atipamezole were administered intramuscularly 30 minutes later. Atipamezole significantly increased the medetomidine-depressed heart rate, respiratory frequency and arterial Po2. The drug also transiently decreased the mean arterial blood pressure but subsequently the blood pressure of the treated group did not differ from that of a group of dogs treated with a placebo.

Animals↗
PubMed1990

T cell precursor migration towards beta 2-microglobulin is involved in thymus colonization of chicken embryos.

beta 2-microglobulin (beta 2m) attracts hemopoietic precursors from chicken bone marrow cells in vitro. The cell population responding to beta 2m increases during the second period of thymus colonization, which takes place at days 12-14 of incubation. The precursors from 13.5 day old embryos were isolated after migration towards beta 2m in vitro and shown to be able to colonize a 13 day old thymus in ovo, where they subsequently acquire thymocyte markers. In contrast these beta 2m responsive precursors did not colonize embryonic bursa, i.e. differentiate into B lymphocytes. During chicken embryogenesis, peaks of beta 2m transcripts and of free beta 2m synthesis can only be detected in the thymus. The peak of free beta 2m synthesis in the thymus and the increase of beta 2m responding bone marrow cells both occur concomitantly with the second wave of thymus colonization in chicken embryo, facts which suggest that beta 2m mediated chemotaxis is involved in the second wave.

Animals↗
PubMed1990

Tissue distribution and appearance in ontogeny of alpha/beta T cell receptor (TCR2) in chicken.

We have performed immunoperoxidase staining on cryostat tissue sections and immunofluorescence analysis on cell suspensions to identify cells expressing the alpha/beta T cell antigen receptor during ontogeny and adult life in chickens. We used the mouse monoclonal antibody, TCR2, which was previously shown to recognize the alpha/beta TCR in chickens. TCR2+ cells were observed in thymic cortex and medulla and in T-dependent areas of spleen, intestine, and cecal tonsils of young adult chickens. Some TCR2+ cells were found in the cortex of bursal follicles and in liver. The first TCR2+ cells appear in thymus on Day 13 of the embryonic life and it is only after hatching that TCR2+ cells begin to migrate to the periphery.

Age Factors↗
PubMed1990

In vitro organ culture of embryonic bursa of Fabricius.

An in vitro method for organ culture of embryonic bursa of Fabricius is presented. It is shown that bursa cells proliferate in in vitro culture as evidenced by [3H]-thymidine incorporation. We assessed the expression of B-cell alloantigen (Bu-la and Bu-lb), class I (B-F) and class II (B-L) antigens of chicken major histocompatibility complex (MHC), and surface immunoglobulin (sIg) on cultured bursa cells using specific monoclonal antibodies (mAb). Cells from 13-day and 14-day embryonic bursae incubated in organ culture for 1 to 2 weeks developed characteristic patterns of surface phenotype observed in adult chicken except for B-F antigen, whose expression was much lower than in vivo. These results indicate that the maturation of bursa cells in organ culture follows the in vivo development, except for the expression of MHC class I antigens. Furthermore, we demonstrate the in vitro repopulation of bursae from cyclophosphamide(cy)-treated chickens by cells from Bu-l antigen disparate normal bursae.

Animals↗
PubMed1990

Changes in lymphocyte subsets and immune competence in very advanced age.

To study the changes in immune system during aging and their effects on patient survival, immune functions of 18 very old (92-107 years) hospital patients were tested. After three years follow-up, the survival of patients and the correlation of immune capacity to lifetime were determined. In the very old patients, the frequency of T lymphocytes was significantly lower than in young adults. This decrease was attributed more to the CD8-positive than to CD4-positive cell subset, leading to generally high CD4/CD8 ratios. The mitogenic responses to phytohemagglutinin (PHA) and concanavalin A (Con A), but not pokeweed mitogen (PWM), were decreased significantly in cultures with isolated lymphocytes, while in whole blood cultures the responses to PHA and PWM but not to Con A were reduced. In very advanced age, there was a significant decrease in the number of B cells, and the ability to produce IgM in vitro was decreased. During the follow-up time, 15 out of the 18 patients died. However, their lifetime was not in correlation with any single immune parameter.

Aged↗
PubMed1990

Reversal of medetomidine sedation by atipamezole in dogs.

Atipamezole reversed the sedative effect of medetomidine in twelve laboratory beagles. The dogs were sedated with medetomidine doses of 20, 40 and 80 micrograms/kg body wt i.m. Atipamezole was injected (i.m.) 20 min later at dose rates two, four, six and ten times higher (in micrograms/kg) than the preceding medetomidine dose. Placebo treatment was included in the study. The deeply sedated dogs showed signs of arousal in 3-7 min and took their first steps 4-12 min after atipamezole injection. The dose-related reversal effect of atipamezole proved to be optimal with doses which were four, six or ten times higher than the preceding medetomidine dose. Drowsiness was found 0.5-1 h after atipamezole injection in 41% of the cases. No adverse effects nor cases of over-alertness or excitement were found.

Adrenergic alpha-Antagonists↗
PubMed1989

B cell maturation in the chicken Harderian gland.

We have characterized maturation of B lymphocytes in the chicken Harderian gland. Expression of Ig genes was studied by using lambda L and mu H chain-specific DNA probes. In unstimulated chickens, the concentration of mu H chain and lambda L chain mRNA in the Harderian gland was observed to be greater than 8 times higher than in the bursa of Fabricius or spleen. By using in situ hybridization, the plasma cells expressing mu mRNA were located in central area of the gland packed around the tubules. Antibodies produced by the Harderian plasma cells were measured from the tears before and after antigenic stimulation. In unstimulated chickens high levels of total IgM, IgA, and IgG were observed. After ocular stimulation with tetanus toxoid, specific antitetanus IgG and IgA antibodies appeared in the tears but IgM antibodies were barely detectable. These results indicate that after antigenic stimulation the Harderian B cells rapidly mature through IgM secretion to the production of IgG or IgA. Southern blot analysis of the Harderian total genomic DNA showed strong rearrangement in the lambda L chain locus. In contrast, the band indicating major rearrangement in the mu H chain locus gave a very poor hybridization signal, indicating deletion of C mu genes in the Harderian gland DNA. As a conclusion, our present data indicate for the Harderian gland a role in terminal B cell differentiation and Ig class switch.

Animals↗
PubMed1989

Bu-1 antigen expression as a marker for B cell precursors in chicken embryos.

Genetically polymorphic cell surface antigen, Bu-1, is expressed on B cells as well as on a subset of macrophages. Bu-1+ cells are also present in embryonic spleen and bone marrow, and these could represent prebursal precursors for B cells and Bu-1+ macrophages. To test the repopulation capacity of these cells we sorted 14-day embryonic spleen cells from Bu-1a-homozygous donors into Bu-1a+ and Bu-1a- fractions and transferred them into age-matched irradiated Bu-1b-homozygous recipients. Four to six weeks after hatching, the recipients were analyzed for Bu-1 chimerism. The results demonstrate that B cell precursors are exclusively present in the Bu-1+ population of 14-day embryonic spleen, whereas the Bu-1+ macrophage subpopulation can be repopulated by either the Bu-1+ or the Bu-1- fraction of these embryonic cells. Bone marrow cells from young chickens could also repopulate the Bu-1+ macrophage subset but not the B cell compartment, thus confirming previous data that postnatal bone marrow does not contain B cell precursors. These results demonstrate that all B cell precursors in the 14-day embryonic spleen carry the Bu-1 antigen, and suggest that there is no lineage relationship between the Bu-1+ cells and macrophages.

Animals↗
PubMed1989

Tolerance to class I major histocompatibility complex antigens in chicken B cell chimeras. Effect of B cell depletion on transferability of tolerance.

B cells from bursa of Fabricius of newly hatched chickens are able to reconstitute the B cell compartment of chemically bursectomized chickens. The resulting B cell chimerism can be detected with monoclonal antibodies against donor B cell alloantigen. Chimeric chickens accept donor-type skin grafts and are unresponsive to donor major histocompatibility complex (MHC) antigens in graft-vs.-host splenomegaly assay and mixed lymphocyte reaction. To study the capability of B cells to induce tolerance to selected MHC antigens, we transplanted class I or total MHC-incompatible bursa cells into cyclophosphamide-treated recipients. The recipients of class I or total MHC-incompatible bursa cells were equally tolerant of donor-MHC antigens. To further analyze the mechanisms of tolerance to class I antigens vs. total MHC, spleen cells from tolerant chickens were transferred to irradiated, histocompatible secondary hosts. The secondary recipients were also unresponsive to bursa cell donor-strain MHC antigens. However, if the chimeric B cells were depleted before the spleen cell transfer, the transfer of tolerance to total MHC was severely inhibited. Instead, most recipients of B cell-depleted spleen cells tolerant of class I antigens were still tolerant of bursa cell donor MHC. Our results indicate differences in the transferability of tolerance to class I antigens vs. entire MHC, although in primary recipients of bursa cells the tolerance is similar. These data suggest that a mechanism that is not dependent on the presence of donor cell chimerism contributes to the maintenance of tolerance to donor class I antigens. The transfer of tolerance to total MHC disparity requires the presence of chimeric cells indicating that donor alloantigen expression is needed for induction of tolerance in the secondary hosts.

Animals↗