PubMed Health⌕ Search

Biomedical subjects

J Tuomi

Publications and source records attributed to J Tuomi.

At least 19 recordsLinked to original sources
PubMed2003

Genetic structure and gene flow in a metapopulation of an endangered plant species, Silene tatarica.

We investigated the distribution of genetic variation within and between seven subpopulations in a riparian population of Silene tatarica in northern Finland by using amplified fragment length polymorphism (AFLP) markers. A Bayesian approach-based clustering program indicated that the marker data contained not only one panmictic population, but consisted of seven clusters, and that each original sample site seems to consist of a distinct subpopulation. A coalescent-based simulation approach shows recurrent gene flow between subpopulations. Relative high FST values indicated a clear subpopulation differentiation. However, amova analysis and UPGMA-dendrogram did not suggest any hierarchical regional structuring among the subpopulations. There was no correlation between geographical and genetic distances among the subpopulations, nor any correlation between the subpopulation census size and amount of genetic variation. Estimates of gene flow suggested a low level of gene flow between the subpopulations, and the assignment tests proposed a few long-distance bidirectional dispersal events between the subpopulations. No apparent difference was found in within-subpopulation genetic diversity among upper, middle and lower regions along the river. Relative high amounts of linkage disequilibrium at subpopulation level indicated recent population bottlenecks or admixture, and at metapopulation levels a high subpopulation turnover rate. The overall pattern of genetic variation within and between subpopulations also suggested a 'classical' metapopulation structure of the species suggested by the ecological surveys.

Bayes Theorem↗
PubMed2002

Experimental infection of laboratory mice and rabbits with several isolates of Borrelia burgdorferi sensu lato; comparison of antigens from different genospecies in serological measurement of immune responses.

Infectivity of and immune responses to 28 Finnish Borrelia burgdorferi sensu lato isolates was studied in 3-4-week-old outbred NMRI and inbred BALB/c/Hy laboratory mice; rabbits were also inoculated. Twenty-one isolates were found to detectably infect mice. A variation among isolates in degree of infectivity was observed. Higher infection rate and higher average ELISA readings were recorded for intradermal than intraperitoneal inoculations. The results suggest differences between Borrelia genospecies in organotropism. The ear was frequently infected by representatives of all genospecies; among high infectivity experiments, this rate was highest, 100%, in infections by Borrelia afzelii. Further differences between genospecies specific organ distributions: B. burgdorferi sensu stricto and Borrelia garinii isolates seemed to infect the bladder relatively more frequently than B. afzelii did; B. afzelii isolates infected heart relatively more frequently than others did. Genospecies specific differences were demonstrated between antigens in reactivity, i.e. in their 'sensitivity' as reagents of ELISA and IFA methods to measure isolate specific immune responses. Antigens from two B. afzelii isolates differed clearly in sensitivity.

Animals↗
PubMed1998

Experimental infection of cattle with several Borrelia burgdorferi sensu lato strains; immunological heterogeneity of strains as revealed in serological tests.

Twenty-three experimental cattle, mainly calves, were each inoculated 1-3 times with one of ten Finnish Borrelia burgdorferi sensu lato strains. All three genospecies were represented. Borreliae were administered mainly by both intravenous (about 10(6) to 10(9) spirochaetes) and intradermal (10(4)) routes, and on six occasions subcutaneously (10(3)) only. For infectivity control and comparison purposes mice and rabbits were inoculated simultaneously. Immune responses in cattle were monitored both with whole-cell sonicate enzyme-linked immunosorbent assay (IgG-ELISA) and indirect immunofluorescent assay (IgM-IgG-IFA). Five Finnish strains and the American strain B31 were used as antigens. No clinical signs of borreliosis were observed. Of the strains, 7/10 were interpreted by the immune responses to have caused relatively short-term subclinical infections of varying intensity. Borreliae could not be isolated from blood or other organ specimens of cattle. A rough estimate of the mean infectious dose in the conditions of experiments is 10(6) to 10(7) organisms. In conclusion, the overall result appears to argue a low susceptibility of cattle to clinical borreliosis, at least when infected by Finnish strains of the agent. Significant antigen-specific differences were observed both by ELISA and IFA in detection and quantification of immune responses. As a rule, the homologous antigen was found to be the most sensitive. Genospecies differences were mostly distinct. Antigens of two Borrelia garinii isolates proved practically equal in sensitivity, whereas major differences were displayed between two Borrelia afzelii antigens. In an IFA study, an American (B31) and a Finnish B. burgdorferi sensu stricto strain proved equally sensitive as antigens. In two relatively strong primary immune responses the antigen-specific measurement differences were such that diagnostically in a cross-sectional study only the homologous antigen or an antigen of the same genospecies would have been sufficiently sensitive to show a positive result.

Animals↗
PubMed1995

Characterization of Finnish Borrelia burgdorferi sensu lato isolates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and with monoclonal antibodies.

Thirty-seven Borrelia burgdorferi strains, isolated in 1992 from Ixodes ricinus in Finland, were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and by immunoblotting and indirect immunofluorescence assay (IFA) with five to nine monoclonal antibodies (MAbs). By SDS-PAGE results and reactivities to MAbs H3TS, J 8.3, I 17.3, and D6, the 37 isolates were assigned to the species B. burgdorferi sensu stricto (n = 7), Borrelia afzelii (n = 17), or Borrelia garinii (n = 13). Twenty more isolates examined only by IFA and with part of the MAbs were distributed as follows: 9 B. burgdorferi sensu stricto and 11 other species. Among 16 of 37 isolates displaying a SDS-PAGE patterns considered typical of that of B. garinii, 3 were negative by the test with MAb D6; the rest were positive. The three MAb D6-negative isolates reacted with MAb J 8.3 but not with MAb I 17.3. It is suggested that these isolates of a previously undescribed type represent atypical B. afzelii strains deficient in the expression of OspB proteins. The misleading species designation by the SDS-PAGE result is described. The IFA results were generally consistent with those obtained by immunoblotting. The exception was for 3 of 29 isolates that were positive with MAb H5332 by immunoblotting but that were IFA negative. In the present material of 57 strains, all 16 B. burgdorferi sensu stricto isolates originated from the Aland Islands. B. afzelii and B. garinii were isolated from all three regions where ticks were collected. The distributive difference seems to offer a basis for comparative clinico-epidemiological studies of Lyme borreliosis.

Animals↗
PubMed1994

Prevalence of Borrelia burgdorferi in selected tick populations in Finland.

The purpose of the studies was to determine the prevalence of Borrelia burgdorferi sensu lato in selected populations of Ixodes ricinus in Finland and to secure strains of the spirochete for further characterization. 1,210 Ixodes ricinus ticks (399 females, 419 males and 392 nymphs) were collected during June to August 1992 by flagging from 8 sites in 3 regions. The frequency of B. burgdorferi infection was determined by isolation in BSK II medium. The species identity of most of the isolates was confirmed with the immunofluorescence method. 67 B. burgdorferi strains were isolated from 8 sites; the prevalence ranged from 2.8% to 7.9%. The overall isolation percentage for adult male ticks was 6.4% (7.5% for females, 5.3% for males); for nymphs, 3.8%. No statistically significant association of the prevalence was observed with either pasture or off-pasture habitats nor with specific geographic region/regions. Prevalence figures were roughly of the same magnitude in areas and parts of the country known to differ in their incidence of human borreliosis. An additional 294 ticks, mainly engorged females, were collected from places outside the main study sites. Of the 7 positive ticks 3 were engorged females, originating from a cow, a dog and a cat, respectively. The results in general demonstrate that tick populations in various parts of Finland quite commonly harbour B. burgdorferi.

Animals↗
PubMed1990

Serum antibody response to Listeria monocytogenes, listerial excretion, and clinical characteristics in experimentally infected goats.

We induced an experimental listeriosis in five goats by oral inoculation of Listeria monocytogenes serovar 1/2a. The resulting generalized bacteremia was reflected by systemic illness in four of the five animals inoculated and by excretion of L. monocytogenes in milk by all five animals. By using an enzyme immunoassay, we recorded a markedly enhanced immunoglobulin G (IgG) antibody response in the two youngest and most seriously ill test animals. In these, the elimination of L. monocytogenes from the gastrointestinal tract occurred simultaneously with the development of the highest antibody levels at 14 to 15 days postinoculation. In the case of the oldest test animal, a preexisting, persistent IgG antibody response was recorded which was associated with the total absence of clinical symptoms and the shortest observed fecal carriage of L. monocytogenes, lasting for only 3 days. Two animals remained practically seronegative, and an IgM antibody response was not recorded for any of the animals. The findings suggest that an association exists between the humoral immune defense against Listeria infections, the clinical course of the infection, and the elimination of the Listeria organisms from the gastrointestinal tract.

Animals↗
PubMed1988

Use of monoclonal antibodies to serotype-specific antigens of Haemophilus pleuropneumoniae serotype 2 in passive immunization.

The prophylactic value of mouse monoclonal antibodies to the pig pathogen Haemophilus pleuropneumoniae was studied. Approximately 250 mg of purified mouse monoclonal antibody specific to capsular antigens of H pleuropneumoniae serotype 2 was given IV to five 9-week-old pigs. Five additional pigs from the same litter served as controls. On the following day, all pigs were given a lethal dose (5 x 10(9)) of H pleuropneumoniae serotype 2 into the trachea. Four controls and 1 pig that was given antibodies died within 24 hours. The surviving 5 pigs developed typical signs of pleuropneumonia. After 6 days, the pigs were euthanatized and their respiratory tracts were examined for pathologic changes. All 5 pigs had pathologic changes, but they were less severe in the 4 pigs that had been given antibodies, compared with those in the control pig.

Animals↗