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Biomedical subjects

A Toivanen

Publications and source records attributed to A Toivanen.

At least 19 recordsLinked to original sources
PubMed1992

IgG and IgA antibody responses against porins in Yersinia-triggered reactive arthritis.

Using an enzyme immunoassay, the development and persistence of serum IgG and IgA class antibody responses against porins, a class of the major outer membrane proteins, were compared between patients who developed reactive arthritis and subjects who did not after Yersinia infection. A significant difference was seen between the two patient groups in the beginning of the disease: those with reactive arthritis had higher levels of IgG and IgA class antibodies against the porins. A similar difference in the IgA class antibodies was also seen at follow-up. This supports the hypothesis of persistence of the pathogen within the arthritic host.

Adolescent↗
PubMed1979

Germinal center formation in BSA-tolerant chickens.

In chickens rendered neonatally tolerant to BSA the germinal center formation was significantly decreased after stimulation with BSA at the age of 3 weeks. At the breakdown of tolerance after the age of 6 weeks the IgG antibody formations recovered before the IgM production. Stimulation of tolerant birds with unrelated antigens resulted in slightly decreased antibody response but the germinal center formation was on the same level as in normal controls.

Aging↗
PubMed1979

Prolonged BCG treatment of melanoma: does it suppress the immune capacity?

The immunological status of seven patients with disseminated melanoma during BCG scarification was followed. As parameters, the total peripheral blood leukocyte and lymphocyte counts, serum immunoglobulin levels, natural ABO blood group antibodies, lymphocyte responses in vitro to PHA and PPD, and skin reactivity against PPD and candidin were followed during a period of 2--36 months. The EAC-rosette-forming cells increased and the E-rosette-forming cells decreased during prolonged BCG therapy. The skin reactions and lymphocyte responses showed in most patients conversion from negative to positive or augmentation at the start of the therapy. Later on, however, the values in most patients dropped before disseminated disease became clinically apparent. In the only surviving patient the values first increased, remained high, and after 100 weeks treatment decreased. After 140 weeks' treatment immunological parameters are similar to pre-treatment levels. The possibility that prolonged intensive BCG treatment might eventually suppress the immune system, and thus result in an enhanced risk of dissemination of the disease, is discussed.

BCG Vaccine↗
PubMed1979

Maturation of bursal stem cells within allogeneic or syngeneic bursal microenvironment: acquisition of postbursal maturity.

Differentiation of bursal stem cells in an allogeneic or syngeneic bursal microenvironment was compared. Bursal stem cells were transplanted into CY-treated 4-day-old recipients and permitted to differentiate in these hosts for 6 weeks. Their maturity degree was thereafter assessed by transplanting them into secondary recipients by using morphologic and functional criteria. As the secondary recipients 4-day-old CY-treated or CY-treated and surgically bursectomized chicks were used. The results obtained demonstrate that bursal stem cells develop to mature postbursal cells also within an allogeneic bursa. They also indicate that although the interaction of different lymphoid cells requires histocompatibility, the interaction between stromal cells in the bursa and lymphoid progenitors is not genetically restricted.

Animals↗
PubMed1978

Is group-specific meningococcal vaccination resulting in epidemics caused by groups of virulent meningococci?

In 1976 routine vaccination against Neisseria meningitidis serogroups A and C was started in the Finnish Armed Forces. A case of fulminant, complicated pneumonia caused by group-Y meningococcus in a vaccinated recruit, prompted a study of the distribution of the meningococcal groups isolated from the recruits in the same unit. 14 (46%) of the 31 isolates from 84 recruits were group Y. Group-Y meningococcus was rarely isolated from unvaccinated controls. These results suggest that widespread vaccination against serogroups A and C may have led to an increase in the frequency of meningococcus group Y.

Bacterial Vaccines↗
PubMed1978

The influence of 5-fluorouracil on cellular and humoral immunity in cancer patients.

The effects of 5-fluorouracil (5-FU) on the immune functions of twelve patients with disseminated cancer were studied, using as parameters the peripheral blood lymphocyte count, serum immunoglobulin levels, titers of natural blood group antibodies, percentages of E and EAC rosette forming cells, and lymphocyte proliferative responses to PHA and PPD. No effects on the humoral immune functions or on the percentages of E and EAC rosette forming cells were observed. 5-FU caused a decrease in the proliferative responses of lymphocytes to PHA and PPD. The patients could be divided into two groups: those surviving for six months or more, and those succumbing earlier. The latter ones had already initially poor proliferative responses, particularly to PPD, and the response strongly decreased during the 5-FU treatment. In the patients with a longer survival time, the effects of 5-FU on the PPD and PHA responses were not as striking.

Antibody Formation↗
PubMed1978

Early ontogeny of germinal center formation in the chicken.

Germinal center formation was studied in the spleen of young chickens immunized in ovo and at the time of hatching. When immunization was performed on day 18 in ovo and on the day of hatching, the first germinal centers were observed at 4 days. This is markedly earlier than in unimmunized chickens, where the first germinal centers appear at the age of 10 days or later. Germinal center formation preceded significant antibody production. The possible role of germinal centers in the generation of immunological memory is discussed in the light of these and earlier observations.

Aging↗
PubMed1977

Alkaline phosphatase in the developing bursa of Fabricius. A comparative study of the cyclophosphamide- and testosterone-induced immunodeficiencies in the chick embryo.

The ontogeny of alkaline phosphatase in the bursa of Fabricius was studied by histochemical and biochemical methods. According to the quantitative determinations, the activity of alkaline phosphatase increased from the 11th to 17th day of incubation--that is, during the time of the lymphoid follicle formation in the developing bursa. The activity was localized in the mesenchymal tissue surrounding the lymphoid follicles. Testosterone given in ovo prevented the appearance of alkaline phosphatase in the bursal mesenchyme but had no effect on the activity of the embryonic liver. In contrast, in ovo treatment with cyclophosphamide had no effect on the alkaline phosphatase in the bursa. By using transplantation of embryonic bursal stem cells, it was further shown that, in contrast to cyclophosphamide, testosterone destroys the capacity of the bursa to serve as a differentiation site for the B-cell lineage. The results indicate that testosterone affects the stromal cells of the bursa, whereas cyclophosphamide destroys only the lymphoid population undergoing differentiation and leaves the bursal stroma intact.

Alkaline Phosphatase↗
PubMed1977

Histocompatibility requirements for cellular cooperation in the chicken: generation of germinal centers.

Cyclophosphamide-treated newly hatched chicks were transplanted with histocompatible, semiallogeneic and allogeneic combinations of B (bursa) and T (thymus) cells from newly hatched donors. At the age of 5 weeks the birds were studied for an anti-SRBC response and for the generation of germinal centers in the spleen. The results of these experiments are summarized as follows. i) Allogeneic bursal stem cells have the capacity to restore the bursal structures of CY-treated recipients, but not the germinal center or anti-SRBC formation. ii) When allogeneic B cells are combined with T cells histocompatible or semiallogeneic with them, a restoration of the germinal center formation is achieved, but not to the same level as observed in normal birds or in CY-treated birds transplanted with histocompatible or semiallogeneic B cells. iii) Allogeneic B cells, even when complemented with T cells histocompatible with them, fail to restore the antibody production against SRBC; this is achieved only after transplantation of B cells histocompatible or semiallogeneic with the recipient. These findings indicate that germinal center formation is dependent on cooperation of histocompatible or semiallogeneic B and T cells, and furthermore, that an additional factor provided by the host is involved. Studies with transplantation of histocompatible and histoincompatible 'empty' splenic stromata revealed that the additional factor is not related to the splenic stroma.

Animals↗