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Biomedical subjects

M Riffelmann

Publications and source records attributed to M Riffelmann.

10 recordsLinked to original sources
PubMed2002

Pertussis of adults and infants.

Bordetella pertussis continues to circulate even in populations where a high vaccine coverage of infants and children is achieved. Cases in adolescents and adults are reported with increasing frequency in many countries. Adults are a reservoir for infections in very young infants, in whom pertussis may be severe and life-threatening. The salient clinical feature of pertussis in adolescents and adults is prolonged coughing, and recognising that pertussis does occur in these age groups is the most important step in its diagnosis. A laboratory diagnosis can be made by bordetella-PCR from nasopharyngeal swabs or secretions and by detection of antibodies, mainly to pertussis toxin; laboratory diagnosis is, however, not well standardised. Vaccination of adolescents and adults is now possible with acellular pertussis vaccines, which are well tolerated, immunogenic, and effective. Adolescent boosters and the vaccination of health-care workers are already included in vaccination calendars in some countries. Vaccine-recommending bodies and national health-care organisations must have locally relevant information on the transmission of pertussis from adults to infants to be able to make decisions on the advisability, feasibility, and priority for booster immunisation against pertussis.

Adult↗
PubMed2001

Stability of antibodies to Bordetella antigens in German adults.

To estimate the rate of asymptomatic exposure to Bordetella pertussis antigens in the German adult population and to evaluate the stability of antibodies to these antigens, antibody levels against Bordetella antigens and their variability over time were measured in German adult blood donors. One hundred forty-six regular blood donors (41 females, 105 males) were tested repeatedly for antibodies of isotypes IgG and IgA to pertussis toxin, filamentous hemagglutinin (FHA) and pertactin over a period of 2-5 years. Overall, 86% and 56% had IgG or IgA antibodies to pertussis toxin, respectively, 100% and 92% had IgG or IgA antibodies to FHA, respectively, and 83% and 93% had IgG or IgA antibodies to pertactin, respectively. One significant titer increase of both IgG anti-FHA and IgG anti-pertactin, one of IgG anti-FHA, and two of IgA anti-FHA as well as one significant decrease of IgG anti-pertussis toxin were observed during an observation period of 480.5 person-years. Antibody concentrations in men and women were not different. The data show that the level of antibodies to pertussis toxin, FHA, and pertactin remains stable over several years. Furthermore, depending on the definition of serological evidence, the rate of significant increases or decreases suggesting unrecognized exposure to Bordetella antigens was estimated to be between <0.2 and 1.0 per 100 person-years in the population studied.

Adhesins, Bacterial↗
PubMed2000

Comparison of five commercial enzyme-linked immunosorbent assays for detection of antibodies to Bordetella pertussis.

Measuring antibodies to Bordetella pertussis antigens is mostly done by enzyme-linked immunosorbent assays (ELISAs). We compared the performance of five commercially available ELISA kits with the help of 65 serum specimens which were repetitively tested for evaluation of the kits. The specimens contained 20 paired serum samples from patients with clinical pertussis, 15 samples were from children vaccinated with a diphtheria-tetanus-acellular pertussis vaccine, seven specimens were taken from an interlaboratory comparison of ELISAs, and there were three reference preparations from the Food and Drug Administration's (FDA's) Laboratory of Pertussis and from our laboratory. Reference values were obtained from the FDA or from results obtained with an in-house ELISA. Commercial ELISAs were compared with respect to their reproducibility and variability, their ability to detect significant titer rises in paired serum samples, their ability to detect an immune response after vaccination, and the comparability of semiquantitative and quantitative results. Reproducibility was generally good (>89%), intra-assay variation ranged from 2.4 to 28.7%, and indeterminate results were recorded in up to 18.5% of all specimens. Most kits correctly identified the antibody response to an acellular pertussis vaccine. None of the commercial kits identified all cases of pertussis correctly, and the sensitivity ranged between 60 and 95%. All five commercial ELISAs showed great discrepancies when comparing semiquantitative results and contained obviously different antigen preparations. Our data suggest that the five commercial ELISAs tested here need further improvement and standardization.

Adolescent↗
PubMed1997

Transmission of GBV-C/HGV from drug-addicted mothers to their babies.

BACKGROUND/AIMS: In 1995, a new flavivirus, GBV-C/HGV was identified. Little information is available on the clinical manifestations and epidemiology of GBV-C/HGV infection. We investigated the risk of mother-to-infant transmission in a group of GBV-C/HGV RNA positive women and followed up the GBV-C/HGV infected babies. METHODS: Twenty-eight anti-HCV positive women, of whom 25 have been intravenous drug users, and their children were included in the study. RNA was extracted from serum, reverse transcribed and amplified with primers from the NS5 region of GBV-C/HGV and 5'-UTR of HCV in a nested polymerase chain reaction. Amplified DNA fragments were gel purified and sequenced; the sequences obtained were subjected to a phylogenetic analysis. RESULTS: Transmission of GBV-C/HGV occurred in 10 (56%) of 18 infants born to GBV-C/HGV positive mothers; all these women were drug abusers. Only one (5%) of 19 babies whose mothers were HCV RNA positive by polymerase chain reaction, was infected with HCV during the follow up. High sequence homology in the NS5 region of GBV-C/HGV isolates in 10 mother-child pairs suggested mother-to-infant transmission. All 10 babies remained GBV-C/HGV RNA positive during follow up (2-12 months). None of the GBV-C/HGV infected infants became icteric or demonstrated any clinical or biochemical signs of liver disease. CONCLUSIONS: Mother-to-infant transmission of GBV-C/HGV may be high, at least in HCV-infected, drug-addicted women. In GBV-C/HGV RNA positive infants the rate of GBV-C/HGV persistent infection is high, but the infection is not accompanied by any symptoms of liver disease.

Base Sequence↗
PubMed1997

Genetic heterogeneity of hepatitis G virus isolates from different parts of the world.

Comparative sequence analysis of a 354 nt fragment of the NS5 region of hepatitis G virus (HGV) isolates was performed to assess two levels of HGV genomic variability: (1) heterogeneity of HGV within an infected individual, and (2) heterogeneity of different HGV isolates. Comparison of nucleotide sequences of DNA clones from two virus isolates demonstrated that in each infected individual HGV is represented by a population of virions with closely related but heterogeneous genomes (quasi-species). Phylogenetic analysis of nucleotide sequences of 42 isolates collected from 14 countries revealed less significant genome variability of HGV as compared to hepatitis C virus. Sequences of all HGV isolates fell into one group of distribution of evolutionary distances. On a phylogenetic tree all HGV sequences segregated into numerous branches. All sequences of isolates from Africa, South and South-East Asia, however, were clustered together and were separated from those of other isolates collected in Europe, North America and Central Asia.

Base Sequence↗
PubMed1996

Rational use of diagnostic tools in hepatitis C.

Six years after the introduction of serological tests for the detection of antibodies to HCV these diagnostic procedures have been improved significantly. The ELISA's of the third generation contain 4-5 fragments of structural and nonstructural proteins which have increased the sensitivity and specificity for antibody detection. Several confirmatory assays have been established to detect non-specific reactions. Viremia in acute and chronic HCV infection can be detected by RT-PCR. However, studies on the quality of PCR results with serum panels in a large number of diagnostic labs indicate the urgent need to standardize the RT-PCR techniques. Quantification of viral genomes during acute and chronic HCV infection seem to be of major importance to predict the response rat to IFN. Quantitative RT-PCR techniques using internal standards and the branched DNA technology have been established. Techniques for genotyping HCV isolates have been introduced which also seemed to be important for prediction of IFN response. Recently serotyping of HCV isolates has been evaluated and seems to correlate well with genotyping by RT-PCI and specific probes. The detection of quasispecies in the 5'NCR may, in the future, be an additional prospective test for the prognosis of IFN treatment.

Enzyme-Linked Immunosorbent Assay↗
PubMed1995

Biomonitoring of urinary aromatic amines and arylamine hemoglobin adducts in exposed workers and nonexposed control persons.

The renal excretion of arylamines in occupationally exposed and nonexposed subjects was measured by a gas chromatography-electron capture detector method. Additionally, in the occupationally exposed persons hemoglobin adduct levels of arylamines were determined by a liquid chromatography-electrochemical detector method, together with the individual acetylator status. The aromatic amines aniline, p-toluidine, 2-naphthylamine, and 4-chloro-o-toluidine were detected in the urine of nonsmoking subjects who were not occupationally exposed to arylamines. Significantly higher concentrations of aniline, o-toluidine, m-toluidine, 2-naphthylamine, and 4-methyl-1,3-phenylenediamine could be observed in the urine of smoking control persons in comparison to nonsmokers. Comparison of smokers and nonsmokers in a group of workers primarily exposed to aniline and 4-chloroaniline revealed significant differences (P < 0.05) in the formation of 4-aminodiphenyl hemoglobin adducts and in the renal excretion of 2-naphthylamine. The slow acetylators in this group produced significantly more hemoglobin adducts of aniline and 4-chloroaniline than did the fast acetylators. In slow acetylators among the smoking workers there was a significant increase in the formation of 4-aminodiphenyl hemoglobin adducts and in the renal excretion of 4-chloroaniline and m-toluidine. The results indicate that there are influences of smoking habits and acetylator status on the levels of arylamine hemoglobin adducts as well as urinary arylamine concentrations. Hemoglobin adducts seem to be good parameters for monitoring aniline and 4-chloroaniline exposure at the workplace, especially if the acetylator polymorphism can be taken into account. 4-Aminodiphenyl hemoglobin adducts might be good parameters for monitoring individual smoking habits. The determination of urinary arylamine concentrations provides additional information concerning acute exposures to aromatic amines.

Amines↗