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Biomedical subjects

G Siegl

Publications and source records attributed to G Siegl.

At least 37 records · Page 2Linked to original sources
PubMed1995

Association between human parvovirus B19 infection and arthritis.

OBJECTIVE: To gain information concerning the association between parvovirus B19 infection and arthritis. METHODS: Blood or synovial fluid, or both, from a total of 77 adult patients with various arthropathies (rheumatoid arthritis 13; mechanical arthropathies 11; crystal induced arthritis 13; idiopathic mono/oligoarthritis 25; suspicion of viral arthritis 15) were tested for the presence of the viral genome and anti-B19 antibodies. B19 DNA in blood and synovial fluid was investigated by nested polymerase chain reaction, and anti-B19 IgM and IgG antibodies were detected in blood by enzyme immunoassay. RESULTS: A recent parvovirus infection was documented by the presence of anti-B19 IgM antibodies in the blood of 13 patients. B19 DNA, together with anti-B19 IgM and IgG antibodies, were detected in the blood of seven patients who had an acute transient arthritis, putatively of viral origin. Viral DNA was detected in a synovial fluid sample and in the blood of one patient with monoarthritis who had an anti-B19 IgG response only. CONCLUSIONS: The prevalence of anti-B19 IgG antibody in these patients with various forms of arthritis (63%) was within the same range as that in the general population (blood donors). However, for the patients with clinical suspicion of viral arthritis, the increased seroprevalence of anti-B19 IgM and the presence of the B19 genome point to an association between human parvovirus infections and acute forms of arthritis.

Adult↗
PubMed1994

Parvovirus B19 infection during pregnancy and development of hydrops fetalis despite the evidence for pre-existing anti-B19 antibody: how reliable are serological results?

BACKGROUND: Primary infection with human parvovirus B19 during pregnancy can lead to fetal hydrops, abortion, or stillbirth. However, reinfection in the presence of pre-existing anti-B19 antibody is generally assumed to have no significant effect on the developing fetus. OBJECTIVES: To describe a case of fetal loss at 28 weeks' gestation associated with parvovirus B19 infection which took place in a 26-year-old woman despite the evidence for pre-existing anti-B19 IgG antibodies. STUDY DESIGN: A nested-PCR assay for parvovirus B19 DNA was performed on maternal and fetal samples. Blood samples were tested by various enzyme immunoassays (EIA) for the presence of both anti-B19 IgM and IgG antibodies. RESULTS: B19 DNA together with anti-B19 IgG antibody were detected in maternal blood at the time of intrauterine fetal demise. Amniotic fluid, chorionic villi and various fetal tissues also tested positive for viral DNA. In retrospect, presence of anti-B19 IgG antibody, but no viral DNA, was repeatedly demonstrated in maternal blood before infection took place. However, the serological results differed with the test system used. CONCLUSIONS: Provided that the positive serological results are reliable, the presence of anti-B19 IgG in blood samples collected as early as four years before pregnancy neither protected the mother from reinfection not the fetus from transplacental infection with B19 virus. However, discrepant (negative) serological results were also obtained depending on the test system used. Therefore, and in the light of the possible severe consequences of B19-infection during pregnancy, the means for assessment of the significance of anti-B19 titers have to be urgently established by development of both qualitative and quantitative anti-B19 IgM and IgG standards.

Journal Article↗
PubMed1994

[Prevention for travel to the tropics].

The Swiss Working Group for Health Advice to Travellers regularly publishes its recommendations for malaria prophylaxis and vaccination as supplement to the 'Bulletin' of the Federal Office of Public Health. In this review the strategy with respect to information, to clever behavior abroad, to chemoprophylaxis and immunization prophylaxis is analyzed. A critical evaluation of emergency self-therapy describes remaining questions in particular.

Antimalarials↗
PubMed1993

Human parvovirus B19 infections: routine diagnosis by a new nested polymerase chain reaction assay.

A nested primer PCR assay was developed to detect human parvovirus B19 in various clinical specimens in a routine diagnostic laboratory. Under optimized conditions the highly specific assay had a sensitivity of less than 10 genome units. For practical reasons, however, this sensitivity was adjusted to 10-100 virus genomes in diagnostic applications. Using clinical specimens from 200 patients with suspected B19 infection, nested PCR was shown to have important diagnostic advantages over the detection of B19 specific antibodies. The data suggest that on the basis of serological data as obtained with currently available test systems a considerable proportion of B19 infections would be misdiagnosed. Examples for the usefulness of the PCR assay in routine diagnosis are given.

Adolescent↗
PubMed1993

Proteins specifically binding to the 3' untranslated region of hepatitis A virus RNA in persistently infected cells.

Establishment of persistency is the common result of hepatitis A virus (HAV) infection in most HAV/cell culture systems. Previous studies provided evidence that shortly before or concomitantly with establishment of persistent infections synthesis of viral RNA is down-regulated. This may be an effect of regulating factors. Using RNA/protein binding assays it was shown that, at the critical time during virus replication, proteins accumulate which interact specifically with a distinct nucleotide sequence (HPE) within the 3' non-coding region of the HAV genome and/or (HME) within the 5' terminal region of the HAV antigenome. The sequences consist of 23 nucleotides (HPE: 5'-AAAUUUUCUUAAAAUUUCUGAGG-3'; HME: 5'-CCUCAGAAAUUUUAAGAAAAUUU-3'). A sequence with 79% similarity was found in the corresponding 3' non-coding region of poliovirus type I (Sabin) RNA. The latter sequence was shown to bind proteins from HAV infected cells but comparable proteins were absent in cells infected poliovirus.

Base Sequence↗
PubMed1993

Persistent human parvovirus B19 infection following an acute infection with meningitis in an immunocompetent patient.

A case in which parvovirus B19 infection persisted over a prolonged period of time in the blood of an immunocompetent patient following an acute infection with meningitis is reported. Using a nested polymerase chain reaction assay the viral genome was detected in cerebrospinal fluid as well as in blood at the time of overt disease and in consecutive blood samples collected for up to nine months.

Adult↗
PubMed1992

Specific diagnosis of parvovirus enteritis in dogs and cats by in situ hybridization.

In a retrospective study, the fixed intestines of 10 dogs and 10 cats with intestinal lesions characteristic of parvovirus infection were assayed for the presence of parvovirus by in situ hybridization and immunohistochemistry. Parvoviral nucleic acid was localized by in situ hybridization in intestinal tissue in all 10 dogs and in nine of the 10 cats, whereas antigen was detected only in seven of 10 canine and eight of 10 feline intestines by immunohistochemistry. We conclude that an aetiological diagnosis can be established with a high degree of certainty by routine histology. Demonstration of the infectious agent by in situ hybridization, however, proves to be a valuable specific tool which allows an exact cellular localization of parvovirus in formalin-fixed, paraffin wax-embedded tissue sections.

Animals↗
PubMed1992

Replication of hepatitis A virus and processing of proteins.

Isolation and propagation of hepatitis A virus (HAV) in cell culture is routinely possible. All primary HAV isolates and most established virus strains, however, show a protracted replication behaviour and tend to establish a persistent infection. Rapidly replicating, cytolytic variant viruses can be selected from persistently infected cultures under distinct conditions. Factors critical for the outcome of HAV infection include the genetics of the virus, the physiological state of the infected cell, the presence of defective interfering particles, synthesis and encapsidation of viral RNA and possibly synthesis and processing of viral proteins. Analysis of the latter events have proved to be difficult. Only seven of the 11 peptides coded for by the HAV genome have been experimentally identified and the sequence of cleavages by which they are released from the precursor polyprotein is still a matter of discussion.

Animals↗
PubMed1992

Genetic relatedness of hepatitis A virus strains recovered from different geographical regions.

A pairwise comparison of the nucleic acid sequence of 168 bases from 152 wild-type or unique cell culture-adapted strains of hepatitis A virus (HAV) revealed that HAV strains can be differentiated genetically into seven unique genotypes (I to VII). In general, the nucleotide sequence of viruses in different genotypes differs at 15 to 25% of positions within this segment of the genome. Viruses from four of the genotypes (I, II, III and VII) were recovered from cases of hepatitis A in humans, whereas viruses from the other three genotypes (IV, V and VI) were isolated only from simian species developing a hepatitis A-like illness during captivity. Among non-epidemiologically related human HAV strains, 81 were characterized as genotype I, and 19 as genotype III. Within each of these major genotypes, there were two distinct groups (subgenotypes), which differed in sequence at approximately 7.5% of base positions. Each genotype and subgenotype has a characteristic amino acid sequence in this region of the polyprotein, with the most divergent genotypes differing at 10 of 56 residues. Strains recovered from some geographical regions belonged to a common (endemic) genotype, whereas strains from other regions belonged to several, probably imported, genotypes. Thus, HAV strains recovered in North America were for the most part closely related at the nucleotide sequence level, whereas in other regions, such as Japan and Western Europe, HAV strains were derived from multiple genotypes or sub-genotypes. These data indicate that patterns of endemic transmission can be differentiated from situations in which infections are imported due to travel.

Amino Acid Sequence↗
PubMed1991

Identification and characterization of incomplete hepatitis A virus particles.

The range of hepatitis A virus (HAV) particles generated during persistent infection of different cell lines was studied. Buoyant density and sedimentation analyses of cell extracts revealed a uniform profile of particles in all cell lines analysed except for BS-C-1 cells. The virion itself usually represented less than 50% of the total mass of virus antigen. A major portion of the antigen was associated with non-infectious, empty particles, which banded at 1.305 g/ml and 1.20 g/ml CsCl, and sedimented in sucrose gradients at 76S and 59S. Empty HAV particles were similar to those of poliovirus with respect to their physical stability and had the characteristic capsid protein content (VP0, VP1 and VP3). An additional RNA-containing particle, probably the provirion, represented only a minor species characterized by a buoyant density of 1.32 g/ml in CsCl and sedimenting at 130S.

Animals↗
PubMed1991

Retrospective study of myocardial canine parvovirus infection by in situ hybridization.

The diagnosis of myocardial canine parvovirus (CPV) infection used to depend on the presence of pathognomonic intranuclear inclusion bodies. The in situ hybridization technique, however, allowed to detect CPV specific nucleic acid in myocardial tissue where no inclusion bodies were found. Hence, we applied this technique to check formalin-fixed paraffin-embedded myocardial tissue from puppies with heart lesions for the presence of CPV. The tissues had been collected between 1977 and 1989. A biotinylated probe was used for in situ hybridization. This way CPV specific nucleic acid was detected in 3 dogs where CPV myocarditis had not been diagnosed on routinely stained slides because of the lack of intranuclear inclusion bodies. However, in spite of the application of the in situ hybridization technique no further myocardial CPV infection was detected in puppies with heart lesions from after 1979, confirming that the number of puppies with myocardial CPV infection declined after that year.

Animals↗
PubMed1990

Sucrose-phosphate synthase is dephosphorylated by protein phosphatase 2A in spinach leaves. Evidence from the effects of okadaic acid and microcystin.

Sucrose-phosphate synthase (SPS) purified from spinach leaves harvested in the dark, was activated by mammalian protein phosphatase 2A (PP2A). Activation of SPS in a fraction from darkened spinach leaves was largely prevented by either okadaic acid or microcystin-LR (specific inhibitors of PPI and PP2A), while inhibitor-2 (a PP1 inhibitor) or Mg2+ (essential for PP2C) were ineffective. In vivo, okadaic acid and microcystin-LR prevented the light-induced activation of SPS and decreased sucrose biosynthesis and CO2 fixation. It is concluded that PP2A is the major SPS phosphatase in spinach. This study is the first to employ microcystin-LR for modulating protein phosphorylation in vivo.

Animals↗
PubMed1990

In situ hybridization for the detection of human parvovirus B19 nucleic acid sequences in paraffin-embedded specimens.

Parvovirus infection of pregnant women leading to a transplacentar infection of the fetus may result in hydrops fetalis, and ultimately in intrauterine death of the fetus. In situ hybridization with a biotinylated as well as with a 35S-labeled probe for human parvovirus B19 was performed on formalin-fixed paraffin-embedded (FFPE) tissue from a fetus suffering from non-immunologic hydrops fetalis. Histology was suggestive of viral infection probably with human parvovirus. Parvovirus DNA could be detected and precisely localized mainly in the nuclei of erythroid precursors cells within fetal blood vessels of all organs examined. There was no detection of B19 nucleic acid in parenchymal cells of the placenta or the fetal organs, nor within maternal blood cells. These findings are in agreement with the well-known properties of animal parvoviruses to replicate exclusively in proliferating cells. Taking into consideration the problems in diagnosing human parvovirus infection by light microscopy, we conclude that in situ hybridization with an appropriate non-radioactive probe is a valuable, rapid and safe complementary detection method for the diagnosis and study of human parvovirus infections. The 35S-labeled probe is more sensitive than the biotinylated probe, but has the disadvantages of lower resolution of the signal, longer duration of the assay, the hazard of radioactivity and the shorter shelf-life of the probe.

Adult↗
PubMed1990

Cloning of the human parvovirus B19 genome and structural analysis of its palindromic termini.

We describe the molecular cloning of the entire 5.6-kb single-stranded DNA genome of the human parvovirus B19 in bacterial plasmids. Stable amplification of the recombinant plasmid DNA was achieved in Escherichia coli JC8111 but not in HB101 cells. Sequence analysis of the cloned DNA shows that the terminal 383 nucleotides at each end of the genome are identical inverted repeats. The distal 365 nucleotides of the repeat represent an imperfect palindrome which presumably folds over to form a hairpin structure. The sequence of the hairpin occurs in two distinct configurations which are related in that one is the inverted complement of the other. Such alternative configurations of the terminal hairpins have been found for all parvoviruses analyzed so far and are referred to as flip and flop.

Base Sequence↗
PubMed1990

Molecular epidemiology of human hepatitis A virus defined by an antigen-capture polymerase chain reaction method.

We describe an immunoaffinity-linked nucleic acid amplification system (antigen-capture/polymerase chain reaction, or AC/PCR) for detection of viruses in clinical specimens and its application to the study of the molecular epidemiology of a picornavirus, hepatitis A virus (HAV). Immunoaffinity capture of virus, synthesis of viral cDNA, and amplification of cDNA by a polymerase chain reaction (PCR) were carried out sequentially in a single reaction vessel. This approach simplified sample preparation and enhanced the specificity of conventional PCR. AC/PCR detected less than one cell culture infectious unit of virus in 80 microliters of sample. Sequencing of AC/PCR reaction products from 34 virus strains demonstrated remarkable conservation at the nucleotide level among most strains but revealed hitherto unsuspected genetic diversity among human isolates. Epidemiologically related strains were identical or closely related in sequence. Virus strains recovered from epidemics of hepatitis A in the United States and Germany were identical in sequence, providing evidence for a previously unrecognized epidemiologic link between these outbreaks.

Animals↗