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Biomedical subjects

P Toivanen

Publications and source records attributed to P Toivanen.

At least 199 records · Page 11Linked to original sources
PubMed1983

Immune capacity of the chicken bursectomized at 60 hours of incubation: failure to produce immune, natural, and autoantibodies in spite of immunoglobulin production.

Chickens surgically bursectomized at 60 hr of incubation were immunized at the ages of 6, 7, 8, and 9 weeks with Escherichia coli lipopolysaccharide, levan, tetanus toxoid, and dinitrophenyl-bovine serum albumin. All antigens were given on each occasion. All embryonically bursectomized (BX) chickens had detectable concentrations of serum IgM, IgG, and IgA. On the whole, the IgG level was markedly decreased and the levels of IgM and IgA were normal. Concentrations of serum immunoglobulins did not change during immunization in the BX chickens. In spite of the production of serum immunoglobulins the BX chickens were unable to respond to the immunization by production of specific antibodies, whereas the control (CO) chickens produced good antibody response to each antigen used. The BX chickens also lacked both natural antibodies to phosphorylcholine, fecal bacteria, rabbit red blood cells (RRBC), and MHC antigens and autoantibodies to the liver, kidney, and thyroidea. Neither were any antibodies to the bursal structures observed. These results support the hypothesis that the bursal influence is not necessary for isotype switch, but is essential for the production of specific antibodies.

Animals↗
PubMed1983

Transferable trimethoprim resistance in three Finnish hospitals.

Resistance to trimethoprim in urinary tract isolates was studied in the Turku City Hospital in 1979 and 1980-81 and in the Turku and Kuopio University Central Hospitals in 1980-81. In the Turku City Hospital no changes occurred during this time in the frequency of strains highly-resistant to trimethoprim (MIC greater than 1000 mg/l) or of those in which transferable resistance was demonstrated. However, the nature of resistance has changed since 1979, when the only transferable pattern was trimethoprim-ampicillin resistance. In 1980-81 over half of the transfer-positive stains transferred only trimethoprim resistance. In the university hospitals the strains highly-resistant to trimethoprim occurred in 36.8% of strains resistant to greater than or equal to 8 mg/l. This is significantly less than 68.7% observed at the same time in the Turku City Hospital. Among the highly-resistant strains the frequency of those transferring resistance was the same in the university hospitals as in the Turku City Hospital.

Bacteria↗
PubMed1983

New recombinants within the MHC (B-complex) of the chicken.

In a search for genetic recombinations within the major histocompatibility complex (MHC) of the chicken, the B-complex, the offspring from matings between heterozygous B15/B21 and B4/B6 animals were analysed by red cell agglutination. Among the progeny, 8,912 informative typings were performed. Four recombinants were found, all separating the B-complex loci B-F and B-G (B-F codes for Class I antigens, B-G codes for an antigen of which there is no known homologue in mammals). B-L (Class II antigen) always followed B-F. Stimulation in graft versus host reactions and in mixed lymphocyte cultures followed B-F/B-L. The mapping distance between the two loci B-F and B-G is in the range of 0.04 centimorgan. The lack of recombinants separating individual B-F loci in this study and in the studies of others might indicate that chicken MHC is less complex than those of mammalian species, but alternative explanations are also possible. So far no serologically defined recombinant separating Class I (B-F) and Class II (B-L) loci has been found.

Absorption↗
PubMed1983

Immune capacity of the chicken bursectomized at 60 hr of incubation: surface immunoglobulin and B-L (La-like) antigen-bearing cells.

Chickens were surgically bursectomized at 60 hr of incubation before the bursal anlage appears. Completeness of the bursectomy was confirmed at autopsy at 10 wk of age. These embryonically bursectomized (Bx) chickens are known to produce immunoglobulins of IgM, IgG, and IgA classes, but so far no specific antibodies have been observed even after heavy immunization. Regarding the appearance of surface immunoglobulin positive (s-Ig+) cells, the most striking effect of bursectomy was observed in the frequency of s-IgG+ cells, which were markedly decreased in the spleen, peripheral blood, and thymus of the Bx birds when compared with the age-matched controls. s-IgM+ cells were significantly decreased in the peripheral blood and s-IgA+ cells in the spleen of the Bx birds. In contrast to these findings, s-Ig+ cells of all three classes were present in normal frequency in the bone marrow. Bursectomy had no effect on the total lymphocyte and other white cell counts in the peripheral blood. Likewise, no effect on the frequency of B-L (Ia-like) antigen-positive cells in different organs was observed.

Animals↗
PubMed1983

Development of natural killer cell function in the human fetus.

NK cell activity of four human premature infants between 28 and 33 wk of gestation and eleven human fetuses at 9 to 22 wk of gestation was tested against the K-562 cell line in a 4-hr 51Cr-release assay. Cord blood lymphocytes from premature infants expressed well-developed NK capacity, although the level of cytotoxicity was lower than that of full-term newborns or adults. Cells prepared from fetal liver displayed cytotoxicity against K-562 targets in four out of eleven fetuses, whereas cells from fetal bone marrow, spleen, and thymus expressed only marginal or negative anti-K-562 killing. NK cell activity in the fetal liver was observed as early as at 9 wk of gestation. The functional NK capacity of premature infants and fetuses was augmented in vitro by IFN-alpha treatment. Fetal cells without spontaneous NK activity did not develop cytotoxicity against K-562 target cells in the presence of IFN-alpha. The present results corroborate the concept of the intrauterine development of human NK cell activity.

Female↗
PubMed1982

Trimethoprim resistance in hospitals.

During November 1980 to April 1981, 1561 urinary tract pathogens were collected from Turku City Hospital, Turku University Central Hospital, and Kuopio University Central Hospital. Resistance of the strains was tested by agar-plate dilution against trimethoprim, sulphamethoxazole-trimethoprim, sulphamethoxazole, ampicillin, and nitrofurantoin. Resistance to trimethoprim (greater than 8 mg/l) occurred in 8.6-12.2% of strains from the university hospitals (Pseudomonas excluded) and 38.3% of strains from Turku City Hospital. Resistance of Escherichia coli occurred in 4.1-6.2% of strains from the university hospitals and 21% of strains from Turku City Hospital. Proteus mirabilis was the most resistant of the clinically important bacterial species with resistance to trimethoprim in 29-78%. Attention is called for in defining the type of hospital used for a particular study: bacterial resistance in different hospitals cannot be compared direct and one hospital is not necessarily representative for a whole country. After seven years' use of plain trimethoprim the prevalence of resistance in the two university hospitals in Finland was similar to that in a London hospital just before plain trimethoprim was registered for use in Britain.

Anti-Bacterial Agents↗
PubMed1982

Migration of erythropoietic and prebursal stem cells from the early chicken embryo to the yolk sac.

Lymphocyte development and ontogenetic changes in erythroid cells have been studied in chick-chick yolk sac-embryo chimeras constructed of histoincompatible partners. The results obtained indicate that the early chick yolk sac produces transiently erythroid stem cells whereas definitive erythrocytes are derived from the intraembryonic stem cells. Such a change from the yolk sac-derived cells into embryo-derived cells is not observed in the lymphocytes which are exclusively derived from the embryo-borne stem cells. Experiments with cell transfers from the chimeric yolk sacs demonstrate that erythropoietic and prebursal stem cells migrate from the early embryo to the yolk sac during the second to the seventh day of incubation. The results obtained also exclude the de novo generation of prebursal stem cells in the yolk sac.

Animals↗
PubMed1982

Alpha-naphthyl acetate esterase activity in human foetal lymphocytes.

Human foetal mononuclear cells from thymus, spleen, liver, bone marrow and peripheral blood at 8-24 weeks of gestation were examined for cytochemical evidence of acid alpha-naphthyl acetate esterase (ANAE) activity. The focal brownish-red ANAE reaction product (T cell staining pattern) was observed in counterstained cytocentrifuged cell smears in the cytoplasm. ANAE-positive lymphoid cells were first observed in the thymus at 9 weeks of gestation. A gradual increase in frequency of ANAE-positive cells in foetal thymus was observed, from about 10% at 14-15 weeks to about 20% at 22-24 weeks of gestation. By 14 weeks of foetal age, spleen and liver contained a few ANAE-positive cells and after 15 weeks of gestation consistent occurrence of ANAE-positive cells was observed in foetal bone marrow and peripheral blood. These results demonstrate that ANAE-positive lymphocytes first appear in the foetal thymus and are subsequently found in the foetal liver, spleen, bone marrow and peripheral blood.

Bone Marrow↗
PubMed1982

Studies on the chicken lymphocyte receptor for aggregated IgG.

Chicken lymphocytes isolated from different lymphoid organs were analyzed for Fc IgG receptor by binding of heat aggregated IgG (agg IgG) in the indirect immunofluorescence test. The binding of agg IgG was shown to be specific for Fc IgG receptor, since IgM and F(ab')2 fractions were bound to the lymphocytes in a much less degree. The highest frequency of agg IgG binding cells, almost 100%, was found in the bursa of Fabricius. In contrast to bursa, only a small percentage of thymus cells bound agg IgG. Dose-dependent experiments showed that binding of agg IgG to thymus cells takes place only at high concentrations of the aggregates whereas bursa cells bind agg IgG also at low concentrations. The finding indicates the existence of high and low avidity agg IgG receptors and/or different density of Fc receptors on bursa and thymus cells. A far lower percentage of EA rosette forming cells than of agg IgG binding cells in the various lymphoid organs may depend on the existence of two different Fc IgG receptors on the chicken lymphocytes.

Animals↗
PubMed1982

Migration of prebursal stem cells from the early chicken embryo to the yolk sac.

Allogeneic yolk sac-embryo chimaeras were constructed by association of B15B15 yolk sac and B2B2 embryo on day 2 of incubation. Five days later yolk sac cells from the chimaeras were injected intravenously into 14-day-old irradiated embryos, using recipients of B2B2 and B15B15 genotypes. One week after hatching, cells in the bursa of Fabricius and peripheral blood erythrocytes were studied for Ia-like antigens and B alloantigens, respectively, to determine whether they were derived from the embryo or yolk sac part of the chimaera. The results obtained demonstrate that prebursal and erythropoietic stem cells migrate from the early embryo to the yolk sac during the 2nd to the 7th day of incubation. They also exclude the de novo generation of prebursal stem cells in the yolk sac.

Aging↗
PubMed1982

Ceftazidime in the treatment of urinary tract infection.

Twenty-nine patients with urinary tract infection were treated with ceftazidime intramuscularly, at a dosage of 1000 mg twice daily for 7 days. The patient series was predominantly geriatric, with a mean age of 70.9 years and including 17 patients over 75 years. Nine had an in-dwelling catheter and azotaemia was found in 14 cases. In this clinically difficult group, a positive bacteriological response to treatment was obtained in 72.9% and, if patients with in-dwelling catheters are excluded, 90% were cured. Ceftazidime-resistant Streptococcus faecalis was cultured before treatment in 6 of the 8 unsuccessful cases. In the remaining 2 treatment failures, Streptococcus faecalis was isolated immediately after treatment. In terms of clinical response to therapy all patients were cured or improved. Treatment with ceftazidime was well tolerated. No subjective side-effects occurred. One patient developed a distinct but transient elevation of liver enzymes, and in 2 cases a negative direct Coombs test was temporarily positive.

Aged↗
PubMed1982

Erythropoiesis and lymphopoiesis in the chick yolk-sac-embryo chimeras: contribution of yolk sac and intraembryonic stem cells.

Lymphocyte development and ontogenetic changes in erythroid cells have been studied in chick-chick yolk-sac-embryo chimeras differing at the B locus antigens. Erythroid cells derived from the yolk sac or from the intraembryonic mesenchyme were demonstrated by indirect immunofluorescence in the peripheral blood of these allogenic chimeras. At 7 days of incubation, yolk-sac-derived red cells represent a majority in the peripheral blood. From 9 days of incubation onwards, embryo-derived erythrocytes appear in increasing proportions, making up approximately 90% of the peripheral blood cells at 17-18 days of development. After hatching, no yolk-sac-derived erythrocytes are found in the peripheral blood. Such a change from the yolk-sac-derived cells into embryo-derived cells was not observed in the lymphocytes, as analyzed using specific anti-B and anti-la antisera for detection of thymus and bursa cells, respectively. Ia-like antigens were detected on bursa cells using a triple layer immunofluorescence system. These results obtained from the allogeneic chimeras indicate that the early chicken yolk sac produces only transiently erythroid stem cells, while intraembryonic stem cells are involved in the production of definitive erythrocytes as well as of lymphocytes, both of T and B cells.

Animals↗
PubMed1981

A rosette assay for identification of Ia-like alloantigens on chicken lymphoid cells.

An Ia-rosette assay for the detection of Ia-like alloantigens on the chicken lymphoid cell surface is described. The method is based on the ability of cells treated with alloantiserum to Ia and then with rabbit antiserum against the Fc portion of chicken IgG, to form rosettes with sheep erythrocytes (SRBC) coated with chicken anti-SRBC IgG antibody. Interference with Ia-rosette formation by Fc IgG receptors was eliminated by pronase treatment which removes Fc receptor activity without affecting Ia antigens. The Ia-rosette assay is at least as sensitive as the triple-layer immunofluorescence test for identification of Ia antigens. In addition, the assay allows morphological study and separation of the rosetting cells.

Animals↗