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E C Claas

Publications and source records attributed to E C Claas.

48 records · Page 3Linked to original sources
PubMed1994

Detection of respiratory syncytial virus by RNA-polymerase chain reaction and differentiation of subgroups with oligonucleotide probes.

The polymerase chain reaction (RNA-PCR) was used for specific detection of respiratory syncytial virus (RSV) genomes in clinical specimens. A set of primers was selected from conserved regions of the 1B and N genes for detection of both subgroups. The primers were found to be RSV specific, all RSV strains generated a 218 bp product, and no RSV specific amplified product was obtained when nucleic acids from a variety of micro-organisms from the respiratory tract were subjected to the RNA-PCR. We took advantage of the sequence heterogeneity of the amplified products to discriminate between the A and B strains by hybridisation with subgroup specific oligonucleotide probes. This additional hybridisation assay increased the sensitivity of the RNA-PCR tenfold. The RNA-PCR was tested on clinical specimens from children with symptoms of an infection of the respiratory tract. The results were compared with isolation of RSV in cell culture and direct immunofluorescence. From 93 specimens tested, 31 were found positive by all three techniques. Six additional positive results were detected using RNA-PCR. From these 37 RSV positive specimens 33 (92%), including all 6 additional positives, were subgroup A and only 4 were subgroup B strains. Thus, the RNA-PCR is a specific and sensitive technique for the detection and subgroup classification of RSV genomes.

Base Sequence↗
PubMed1994

Infection of children with avian-human reassortant influenza virus from pigs in Europe.

Pigs have been proposed to act as the intermediate hosts in the generation of pandemic human influenza strains by reassortment of genes from avian and human influenza virus strains. The circulation of avian-like H1N1 influenza viruses in European pigs since 1979 and the detection of human-avian reassortants in pigs raises the question of whether these viruses actually have the potential to transmit and cause disease in humans. We now report the serologic and genetic characterization of two human influenza A viruses (A/Netherlands/5/93 [H3N2] and A/Netherlands/35/93 [H3N2]) that caused influenza in children in The Netherlands in 1993. The results show that these viruses are human-avian ressortants that were generated and currently still are circulating in European swine. This shows the pivotal role that pigs can play in the generation and transmission of avian influenza virus genes to humans and their potential to generate a new human pandemic strain.

Animals↗
PubMed1993

Prospective application of reverse transcriptase polymerase chain reaction for diagnosing influenza infections in respiratory samples from a children's hospital.

A prospective clinical evaluation of the reverse transcriptase polymerase chain reaction (RNA PCR) for detection of influenza viruses was carried out with specimens from 342 patients of a children's hospital in The Netherlands. The RNA PCR, carried out directly on the specimens without an organic extraction, showed a sensitivity and specificity which are superior to those of direct immunofluorescence and comparable to those of cell culture combined with immunofluorescence (culture/IF). Negative results can be obtained within 2 days by the RNA PCR but may take up to 14 days by culture/IF. Because culturing is the standard technique for the detection of respiratory viruses, at this moment there are no strong arguments to replace culture/IF with RNA PCR for the detection of influenza A virus.

Base Sequence↗
PubMed1992

Infections of the cervix uteri with human papillomavirus and Chlamydia trachomatis.

Apart from infection with human papillomavirus (HPV), other microorganisms may be involved in the development of cervical neoplasia. To study concomitant infections with HPV and Chlamydia trachomatis, cervical specimens from 4 groups of women were examined for the presence of these microorganisms by the polymerase chain reaction. The first group consisted of 143 consecutive samples from women with no cytological abnormalities who participated in a triennial screening program to prevent cervical cancer. In this group 2 samples were found positive for HPV and 2 additional samples were found positive for C. trachomatis. In the second group of 46 cytologically abnormal smears, HPV DNA was detected in 71.7% of the samples and C. tra chomatis in 4.3%. In a third group of 94 histological abnormal biopsies, the HPV prevalence ranged from 15% in mild dysplastic lesions up to 92% in invasive cervical carcinomas. Only 2 biopsies of this group (2.1%) were found positive for C. trachomatis. Finally, a group of cervical scrapes was obtained from women attending a clinic for sexually transmitted diseases. In 52 samples positive for C. trachomatis and 60 samples negative for C. trachomatis, no significant (P = 0.57) difference in the frequency of HPV infections was found (11.5% and 8.3%, respectively). The data show that in these study groups HPV and C. trachomatis are independently occurring agents.

Base Sequence↗
PubMed1992

Type-specific identification of influenza viruses A, B and C by the polymerase chain reaction.

The aim of this study was to develop a polymerase chain reaction for specific detection of influenza A, B, and C RNA genomes. Three primer sets were selected from conserved regions of the genome coding for the non-structural proteins and were tested on 61 influenza A (22 H1N1, 9 H2N2, and 30 H3N2), 11 influenza B, and three influenza C isolates. Specific amplified products were obtained with all these strains after electrophoresis on a 2% agarose gel. The specificity of the reaction was increased by hybridization with oligonucleotide probes. When nucleic acids from a variety of micro-organisms from the respiratory tract were subjected to the PCR with these primers, no specific amplified products were generated. The sensitivity of the technique was found to be at the subpicogram level. The RNA-PCR was applied to 21 clinical specimens from patients with a culture/IF proven influenza infection. Six influenza A positive patients and 13 influenza B positive patients could be confirmed in the RNA-PCR. In two cases, influenza B positive IF specimens were found negative by the PCR. No virus could be isolated on eggs or tissue culture from these samples. RNA-PCR is a specific and sensitive technique for the detection of influenza virus genomes.

Base Sequence↗
PubMed1992

Human papillomavirus and the three group metaphase figure as markers of an increased risk for the development of cervical carcinoma.

In this study, the presence of atypical mitotic figures and human papilloma virus (HPV) genomes was related to the degree of cervical intraepithelial neoplasia (CIN) or microinvasive carcinoma (MIC) as found in 94 paraffin-embedded biopsies from cervical lesions. The results showed that the frequency of three group metaphase (TGM) figures, a special kind of atypical mitotic figure, as well as the presence of HPV 16 and 18 genomes increased with the degree of cervical intraepithelial neoplasia. TGM figures were observed in 24% of CIN2, up to 61% in CIN3 lesions, and in 83% of the microinvasive cervical carcinomas. HPV genomes were detected in 15% of CIN1, up to 75% in CIN3 lesions, and in 92% of the invasive carcinomas of the cervix. The combination of these two markers showed even a better association with a higher degree of cervical intraepithelial neoplasia. The results of these studies suggest that detection of particular HPV types, mainly HPV 16 and 18, and the presence of TGM figures can be considered as markers that indicate an increased risk for progression of cervical intraepithelial neoplasia to invasive carcinoma.

Carcinoma in Situ↗
PubMed1989

Use of anticontamination primers in the polymerase chain reaction for the detection of human papilloma virus genotypes in cervical scrapes and biopsies.

A reliable application of the polymerase chain reaction (PCR) for detection of the human papilloma virus (HPV) genotypes in cervical smears and biopsies was developed. Primers flanking the HPV cloning site were used to avoid detection of cloned HPV plasmids. These anticontamination primers were used for the specific detection of HPV 6, 11, 16, 18, and 33 in cervical scrapes that had been tested previously for HPV with a combined modified filter in situ hybridization (modified FISH) and dot blotting procedure. The PCR appeared to be superior. Two groups of women were screened for HPV genotypes. Group A consisted of women belonging to a regularly screened population, and group B contained women attending a gynaecological clinic. It appeared that the overall prevalence of HPV in cytologically normal scrapes in the first group was 6%, whereas in the second group 12% was found. In scrapes with cytological dysplasia, the prevalence of HPV in group A and B was approximately 40% and 60%, respectively. HPV 16 was present predominantly. In biopsies of squamous cell carcinomas of the cervix uteri, an HPV prevalence rate of 90% was found, all of which contained only HPV 16 and 18. These data indicate an important role for HPV detection in the screening of cervical scrapes to identify women with an increased risk of cervical cancer.

Adult↗
PubMed1989

Human papillomavirus detection in paraffin-embedded cervical carcinomas and metastases of the carcinomas by the polymerase chain reaction.

The polymerase chain reaction (PCR) is used for human papillomavirus (HPV) detection in paraffin-embedded tissue. The specificity of the reaction is unaffected by the method of fixation used before embedding into paraffin. Five HPV 16, 18, 31, and 33 DNA in situ hybridization (DISH)-negative cervical carcinomas were subjected to the PCR. In two patients, HPV 16 DNA could be detected in the cervical squamous cell carcinomas and also in their lymph node metastases. One patient with an adeno-carcinoma of the cervix was found positive for HPV-18. A lymph node of this patient was HPV 18 positive as well. In the tumors of the remaining two patients, no HPV 16, 18, or 33 DNA was detected by the PCR. Both negative patients had cervical squamous cell carcinomas. One had a bladder metastasis, whereas the other had a lymph node metastasis and an additional distant metastasis in the lung. HPV DNA positivity in cervical carcinomas correlated with HPV prevalence in the metastases. This relationship can be of use for diagnostic purposes in the pathologic analysis of metastases.

Blotting, Southern↗
PubMedDate not supplied

Detection of infections of the eye with Chlamydia trachomatis by the polymerase chain reaction.

The aim of this study was to test the diagnostic feasibility of the polymerase chain reaction (PCR) for detection of infections with Chlamydia trachomatis in eye swabs from patients with conjunctivitis, and to establish the basic technique of the PCR for epidemiological survey. The results of the PCR were compared with the Mikro Trak immunofluorescence assay (IFA). From 49 specimens of patients with conjunctivitis, 31 were found positive by PCR (63%) and 23 by IFA (47%). On the other hand, in 10 normal eye specimens and 10 non-Chlamydia trachoma conjunctivitis specimens no Chlamydia trachomatis was detected.

Antibodies, Bacterial↗
PubMedDate not supplied

Human influenza virus A/HongKong/156/97 (H5N1) infection.

Introduction of influenza viruses with gene segments of avian origin into the human population may result in the emergence of new pathogenic human influenza viruses. The recent infection of a 3-year-old boy with an influenza A (H5N1) virus of avian origin can be considered as an example of such an event. However, this virus, influenza A/Hong Kong/156/97 (H5N1) and the 17 additional H5N1 viruses isolated from humans by the end of 1997 lack the ability to spread efficiently amongst humans and therefore have limited pandemic potential. However, the possibility of reassortment of these viruses with currently circulating human viruses illustrates the need for pandemic preparedness.

Animals↗