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Biomedical subjects

B Christenson

Publications and source records attributed to B Christenson.

At least 19 recordsLinked to original sources
PubMed1992

A 15-year surveillance study of antibodies to herpes simplex virus types 1 and 2 in a cohort of young girls.

A cohort of 839 young girls at the ages of 14 and 15 years was screened for total antibodies to herpes simplex virus (HSV) and, if positive, for specific antibodies to HSV-2, by means of a sensitive, enzyme-linked immunosorbent assay (ELISA). The cohort was followed from 1972-1987. Blood samples were obtained on six occasions during these 16 years. In total, 2270 blood samples were taken. The number of sero-converting girls was studied in relation to calendar time. Two methods were constructed for the statistical analyses. The first of these gave an estimate of the sero-prevalence at different points in time. This analysis showed that the sero-prevalence which was 23% against HSV-1 in 1972 had increased to 36% in 1976. At the end of the study in 1987, 50% of the cohort had sero-converted against HSV-1. The proportion of girls who had sero-converted against HSV-2 was 0.4% in the 14-15-year-olds and had reached 22% by the end of the study. The second statistical method used all the available information implicit in the observations so as to obtain a maximum-likelihood (ML) estimate of the prevalence. The ML estimates were slightly more precise, but the two estimates did not differ significantly. The observations were further analysed by the Mantel-Haenszel test in order to see if there was any dependence between positivity to HSV-1 and HSV-2 respectively but none was found.

Adolescent↗
PubMed1991

Changes of the immunological patterns against measles, mumps and rubella. A vaccination programme studied 3 to 7 years after the introduction of a two-dose schedule.

A two-dose vaccination programme using a combined measles, mumps and rubella vaccine (MMR) and administration at the ages of 18 months and 12 years was introduced in 1982. The 12-year-old schoolchildren were tested yearly from 1985 to 1989 on serum samples obtained prior to and after vaccination. Each year between 420 and 756 children were tested. The method used for antibody testing was the haemolysis-in-gel (HIG) assay. For measles also the enzyme-linked immunosorbent assay (ELISA) and the neutralization titre (NT) were applied. Only minor variations of the prevaccination immunity to measles were seen during the period 3-7 years after introduction of the programme. The age groups studied had partly been vaccinated against measles earlier. Between 12 and 16% lacked prevaccination immunity. In contrast the immunity to mumps and rubella of the 12-year-old children decreased considerably during the study period. No general vaccination against these diseases had been performed. Thus the susceptibility to mumps increased from 14% in 1985 to 39% in 1989 and to rubella from 41 to 57%. The seroconversion rate of children seronegative for measles was high, i.e. 100% in 1985 and later varied between 96 and 97%. For mumps, the seroconversion rate was lower and varied between 72 and 88%. All sera converted to rubella. During the follow-up period there was a declining incidence of measles, mumps and rubella. The relationship between the vaccination and reduction of disease and natural immunity strongly suggests that the association is causal and that this vaccination policy reduced the transmission of infection.

Antibodies, Viral↗
PubMed1991

Immunity and immunization of children against tetanus in sweden.

Tetanus antitoxin titres were determined in sera of 457 children, 6-, 10- and 16- year-old. Primary vaccination against tetanus had been given as 3 doses of DPT or DT vaccine at intervals of 4-6 weeks beginning in the 2nd or 3rd month of life. A booster dose is offered to schoolchildren at 8-10 years of age. As boosters, the children were given 0.1, 0.25 or 0.5 ml of diphtheria/tetanus toxoid (DT) containing 7.5 Lf/ml tetanus toxoid. The antitoxin titres against tetanus were much higher than those against diphtheria found in previous studies. Blood samples tested from 68 children, 5-year-old, who had been given basic immunization according to a spaced time schedule showed that 97% of the children had levels greater than 0.1 IU/ml. Prior to booster injection of the 6-year-old children, 1% lacked protective titre levels (greater than or equal to 0.01 IU/ml). 53% had antitoxin titre levels of greater than or equal to 0.01 - less than 0.1 IU/ml and 46% had levels of 0.1 IU/ml. The corresponding figures for the 10-year-old were 6, 65 and 29%, and for the 16-year-old 2, 7 and 91% respectively. After a booster injection high antitoxin levels were seen in all children. 95% had levels greater than 1 IU/ml irrespective of vaccine dose.

Adolescent↗
PubMed1990

Methods for screening the naturally acquired and vaccine-induced immunity to the measles virus.

Since the measles, mumps and rubella (MMR) vaccine was introduced into Sweden in 1982, a yearly evaluation of the immunity patterns and sero-conversion rates in 12-year-old children has been carried out. Since 1977, about half of the pre-school children have been vaccinated against measles. This study includes two study groups. (1) 145 selected pre- and post-vaccination samples tested by the haemolysis-in-gel (HIG) technique and the neutralization test (NT). The selection was made from 1298 12-year-old schoolchildren in 1986 and 1987, whose pre-vaccination sera had shown negative or borderline reactions to the HIG technique. (2) Consecutive pre- and post-vaccination samples obtained from 190 vaccinees in 1988 and 1989. These samples were studied by an enzyme-linked, immunosorbent assay (ELISA) and compared to the NT. The NT and the HIG tests yielded congruent results in early post-vaccination sera from children susceptible to measles prior to vaccination. In late post-vaccination samples, the NT and the HIG tests were discordant, up to 25% of the NT-positive samples being negative by the HIG technique. In no instance did the ELISA produce discrepant results, compared with those of the NT. With both this assays significantly lower antibody levels were detected in late post-vaccination sera (8-11 years) compared to early post-vaccination samples (P less than 0.001) or to sera obtained after natural infection.

Antibodies, Viral↗
PubMed1990

Methods for screening the naturally acquired and vaccine-induced immunity to the mumps virus.

Since the introduction of the measles, mumps and rubella (MMR) vaccine in Sweden in 1982, a yearly evaluation of the immunity pattern and seroconversion rate of 12-year-old children has been carried out. To be able to realize large-scale, follow-up studies, techniques have to be used which are not too labour-intensive and time-consuming but are sensitive enough to detect past immunity and post-vaccination titres. We report tests with haemolysis-in-gel (HIG) technique and an enzyme-linked, immunosorbent assay (ELISA) compared with neutralization (NT) for the detection of mumps antibodies. This study comprises 226 paired serum samples obtained between 1985 and 1989. One hundred and forty-one of the paired samples had been selected because they had given negative or borderline readings, using HIG technique. The remaining samples were consecutive pre- and post-vaccination sera obtained in 1989 from 85 vaccinees from one area in Sweden. HIG technique gave both false positive and false negative readings, compared with NT as also the false positive sera were detected. Non-inactivated sera could not be used in the NT test against mumps virus, owing to unspecific NT reactions. No differences between non-inactivated and inactivated sera by NT were seen, as against other paramyxoviruses. Cross-reactivity between mumps and parainfluenzae in NT tests was not demonstrated. The ELISA test proved more reliable and specific than HIG and was more sensitive than NT. Some post-vaccination sera from vaccinees who failed to seroconvert by NT contained high levels of mumps antibody detectable by the ELISA.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Viral↗
PubMed1990

Responses to rubella, tetanus, and diphtheria vaccines in otitis-prone and non-otitis-prone children.

Delayed immunologic maturation--among other things based on a selective lack of antibodies against some acute purulent otitis media (AOM)-associated pneumococcal types--has been proposed in children with recurrent AOM (rAOM). To further elucidate the immunologic response in these children, we compared the antibody responses to diphtheria, tetanus, and rubella vaccinations in 13 children with rAOM and 29 children without AOM. The children took part in a prospective study from birth to the age of 3 years. The antibody response to the rubella vaccine was significantly lower in the children with rAOM. The responses to tetanus and to diphtheria did not differ between children with and without rAOM. Thus, the results indicate that in addition to the known lack of antibodies against pneumococcal polysaccharide antigens, a lower antibody response against at least one protein antigen may exist in otitis-prone children.

Antibody Formation↗
PubMed1989

MALA-2, mouse homologue of human adhesion molecule ICAM-1 (CD54).

In humans, lymphocyte adhesion to cells is mediated by the protein heterodimer CD11a/CD18 (Leu-CAMa, LFA-1) and its ligand CD54 (ICAM-1). Although the murine CD11a/CD18 is well characterized, the mouse homologue of human ICAM-1 has not been identified. In the present study a rat monoclonal antibody to the murine lymphocyte activation antigen MALA-2 was found to inhibit in a dose-dependent manner the phorbol ester-enhanced aggregation of mouse lymphoblasts, an adhesion-specific assay, and hence to define an adhesion molecule. By immunofluorescence flow cytometry the antigen expression was low on spleen cells but it largely increased after stimulation with mitogens. The antigen was expressed by some, but not all, lymphoid cell lines, and myelomonocytic and mastocytoma cells were also positive. In frozen tissue sections MALA-2 was mainly detected on germinal center B cells, dendritic cells, macrophages and vascular endothelium, including high endothelial venules. Cell surface labeling followed by immunoprecipitation and gel electrophoresis indicated that the antigen is a sialoglycoprotein which has a relative molecular mass of 95 kDa and displays a faster electrophoretic mobility under non-reducing conditions. The function, cellular distribution and molecular properties of MALA-2 are indistinguishable from those of human ICAM-1.

Animals↗
PubMed1989

Immunity and immunization of children against diphtheria in Sweden.

The level of immunity to diphtheria and the effect of vaccination with different doses of diphtheria toxoid was investigated. The 457 study children, 6, 10 and 16 years of age, had as infants received routine primary vaccination with three doses of diphtheria-tetanus-toxoid or diphtheria-tetanus-pertussis vaccine, and the 16 year-olds also had received a booster dose of tetanus with a small dose of diphtheria at the age of ten. Prior to the study booster, 15% of the 6-year-olds had antitoxin levels against diphtheria less than 0.01 IU/ml, the given minimum level for protection. Of the 10-year-olds, 48% had titres less than 0.01 IU/ml, while the corresponding figure for the 16-year-olds was 24%. After a booster injection of 0.1, 0.25 or 0.5 ml of diphtheria-tetanus vaccine, more than 97% of the children showed titre levels greater than or equal to 0.1 IU/ml, while levels of greater than or equal to 1 IU/ml, indicating titres sufficient for long-term protection, were attained by 23-96%. Systemic reactions were few and moderate. Local reactions were of little clinical significance. In a group of 5-years-olds given diphtheria-tetanus primary vaccinations over wider intervals, only 1.4% had antitoxin titres less than 0.01 IU/ml. The results show a need for serologic monitoring of vaccination programmes.

Adolescent↗