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Biomedical subjects

C Schalén

Publications and source records attributed to C Schalén.

11 recordsLinked to original sources
PubMed1992

A one-year study of streptococcal infections and their complications among Ethiopian children.

Post-streptococcal complications are known to be common among Ethiopian children. Little is known, however, about the epidemiology of beta-haemolytic streptococci in Ethiopia. A total of 816 children were studied during a one-year period: 24 cases of acute rheumatic fever (ARF), 44 chronic rheumatic heart disease (CRHD), 44 acute post streptococcal glomerulonephritis (APSGN), 143 tonsillitis, 55 impetigo, and 506 were apparently healthy children. Both ARF and APSGN occurred throughout the year with two peaks during the rainy and cold seasons. The female:male ratio among ARF patients was 1.4:1 and 1:1.9 among APSGN. The monthly carrier rate of beta-haemolytic streptococci group A varied from 7.5-39%, average being 17%. T type 2 was the most frequent serotype. Marked seasonal fluctuations were noted in the distribution of serogroups among apparently healthy children. Beta-haemolytic streptococci group A dominated during the hot and humid months of February-May. Strains were susceptible to commonly used antibiotics, except for tetracycline.

Carrier State↗
PubMed1979

Upper respiratory tract spread of group B streptococci type I b in a kindergarten.

In a kindergarten with 42 children and 17 female staff members, an epidemic of group B streptococcal carriage in the upper respiratory tract occurred. In the middle of February 1978, 6 children and 5 adults carried type I b streptococci in the throat while only 2 of these 11 were carriers 2 weeks later. Only one other streptococcus, belonging to type II, was found in the throat specimens. Five strains other than type I b were found in the urogenital tract of the staff. Three type I b throat carriers were also urogenital carriers of this type. The spread of type I b streptococci could have resulted from co-spreading with other upper respiratory tract pathogens found, including group A streptococci of type 12. Haemophilus influenzae, Branhamella catarrhalis and pneumococci. Estimation of antibodies with radiolabelled protein A indicated an immune response to type I b, but not to types I a, II or III group B streptococci in the staff compared with healthy blood donors.

Adolescent↗
PubMed1979

Precipitation of streptococcal peptidoglycan by human sera: influence of anti-immunoglobulins.

Antibodies to streptococcal peptidoglycan (PG) were detected by gel-precipitation in 38% of sera from blood donors and in 71% of sera with a Waaler-Rose test titre of greater than or equal to 1:64. Twenty-six rheumatoid arthritis sera revealed patterns of interference with complete or partial fusion between PG and aggregated human IgG while none of the sera precipitating both these preparations showed non-interference. The reactions were interpreted as denoting interference between the PG-antibody complexes and aggregated IgG. Conversion of some non-precipitating blood donor sera to PG precipitation was obtained by addition of isolated rheumatoid factor, in itself not precipitating PG, to the sera. Thus, the high frequency of PG precipitation among rheumatoid arthritis sera could--at least in part--be attributed to the participation of anti-IgG in the reaction.

Antibodies, Anti-Idiotypic↗
PubMed1979

Interaction of the Fc part of IgG with Lancefield extracts of hemolytic streptococci. Strain specificity and activity.

Lancefield extracts of 19 types of group A streptococci as well as one group C and one group G strain were examined for agglutination of human red cells coated with various anti-Rh antibodies. Fourteen extracts agglutinated one or more of the coated cell samples, while five did not. The agglutination was inhibited by Fc but not by Fab fragments of human IgG. After mouse passages, three of the non-agglutinating strains acquired agglutinating capacity. At least three different reactivities were distinguished by the action of the extracts on IgG1 and IgG3 coated cells, respectively. Two of the streptococcal extracts, agglutinating the same anti-Rh coated cells, could be further differentiated in hemagglutination inhibition (HAI) experiments using purified IgG3 myeloma proteins. Five selected agglutinating systems were inhibited by purified myeloma proteins of the IgG1, IgG2, and IgG4 subclasses. IgG3 proteins inhibited only two of the five HAI systems.

Antibodies, Bacterial↗
PubMed1979

Demonstration of the non-identity between the Fc receptor for human IgG from group A streptococci type 15 and M protein, peptidoglycan and the group specific carbohydrate.

After electrophoresis of an alkaline extract of type 15 group A streptococci, three main precipitation lines were obtained in diffusion experiments against commercial human polyclonal IgG (lines 1, 2 and 3). Nineteen of 23 sera (83%) from apparently healthy human individuals gave line 3, while 6 of them (26%) gave line 1. The sera giving line 1 did also give line 3. Line 2 was obtained with 2 sera only, also giving lines 1 and 3. Line 3 was caused by a streptococcal Fc-receptor for human IgG, since the line could be displaced by addition of Fc-fragments, but not Fab-fragments of pooled human IgG. Line 1 was shown to be different from line 3, since (1) line 1 was suppressed in contrast to line 3 on absorption of a human serum or commercial polyclonal human IgG with S. aureus; and (2), line 1 was suppressed by Fab-fragments but not Fc-fragments of polyclonal human IgG. Line 2 could be inhibited by addition of peptidoglycan to commercial polyclonal human IgG or a human serum investigated. Another line, 4, obtained in diffusion experiments involving electrophoretically separated alkaline extract of type 15 group A streptococci was type-specific as shown by rabbit antisera to streptococci type M1, M8, M15, and T44, and disappeared on trypsinization of the extract. The component responsible for line 4 in the streptococcal extract, judged to be type-specific M protein, had a mobility different from the component responsible for line 3 in electrophoresis.

Bacterial Proteins↗
PubMed1977

A simple method for demonstrating gel-precipitating human anti-immunoglobulin antibodies.

The use of aggregated human IgG for the detection of anti-immunoglobulin antibodies by double immunodiffusion in gel is described. Of rheumatoid arthritis sera, 54 of 56 sera having a Waaler-Rose test titre of greater than or equal to 1:16 contained antibodies to aggregated IgG, in contrast to only 2 of 52 sera from blood donors. Furthermore, after 2-mercapto-ethanol treatment anti-IgG was still demonstrated in 5 of 16 sera.

Antibodies, Anti-Idiotypic↗
PubMedDate not supplied

Chlamydia trachomatis antigen detection by Chlamydiazyme combined with Chlamydia Blocking Reagent verification.

Several options exist for the detection of chlamydial infection in a routine laboratory setting. Enzyme immuno assay (EIA) technology offers rapid turn around of results and is less technically demanding than chlamydial cell culture. In addition, recently introduced EIA confirmatory reagents have the potential to improve the accuracy of EIA detection. We have evaluated one such confirmatory reagent (Chlamydia Blocking Reagent, Abbott Laboratories) to determine the accuracy of the Chlamydiazyme EIA with special regard to interpretation of low absorbance values. An initial series of 192 male urethral specimens showed that use of a lowered cut off level (absorbance value 0.05) compared with that recommended by the manufacturer increased sensitivity of the EIA from 0.73 to 0.83, thus motivating studies on this interpretative modification. Of 1101 EIA reactive specimens, 65% were determined to be chlamydia positive by the Chlamydia Blocking Reagent. The proportion of female cervical specimens that did not confirm positive was elevated compared with male urethral specimens, 43% vs. 5.7% respectively. In samples yielding absorbance from the recommended cut off level to 0.05 (approximately 50% below), the corresponding figures were 78% and 14% respectively. In 85 selected EIA reactive samples, examination by a direct immunofluorescence staining assay (DFA) (MicroTrak, Syva Inc.) revealed elementary bodies in 85% of 67 blocking test positive and in 24% of 18 blocking test negative samples. The possibility that Gram-negative bacteria were responsible for unconfirmed EIA reactive specimens was investigated using bacterial suspensions. While EIA reactivity was noted with several strains for Gram-negative bacteria, both the blocking reagent and DFA correctly verified the absence of chlamydial antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Bacterial↗